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TonyKim9401TonyKim9401
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Merge pull request #2259 from ys-han00/main
[ys-han00] WEEK 09 solutions
2 parents 8dadc2f + 197e091 commit e3b2068

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‎linked-list-cycle/ys-han00.cpp‎

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/**
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* Definition for singly-linked list.
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* struct ListNode {
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* int val;
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* ListNode *next;
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* ListNode(int x) : val(x), next(NULL) {}
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* };
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*/
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// class Solution {
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// public:
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// bool hasCycle(ListNode *head) {
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// if(!head)
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// return false;
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// set<ListNode*> check;
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// check.insert(head);
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// while(head) {
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// if(head->next && check.find(head->next) == check.end())
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// check.insert(head);
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// else if(head->next && check.find(head->next) != check.end())
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// return true;
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// head = head->next;
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// }
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// return false;
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// }
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// };
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// class Solution {
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// public:
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// bool hasCycle(ListNode *head) {
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// while(head) {
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// if(head->val) {
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// if(head->val == INT_MAX)
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// return true;
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// head->val = INT_MAX;
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// }
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// head = head->next;
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// }
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// return false;
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// }
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// };
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class Solution {
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public:
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bool hasCycle(ListNode *head) {
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ListNode* slow = head;
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ListNode* fast = head;
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while(fast && fast->next) {
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slow = slow->next;
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fast = fast->next->next;
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if(slow == fast)
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return true;
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}
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return false;
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}
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};
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‎maximum-product-subarray/ys-han00.cpp‎

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class Solution {
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public:
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int maxProduct(vector<int>& nums) {
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int prod_min = 1, prod_max = 1, ans = nums[0];
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for(int num : nums) {
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int tmp = prod_min;
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prod_min = min(prod_min * num, prod_max * num);
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prod_min = min(prod_min, num);
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prod_max = max(tmp * num, prod_max * num);
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prod_max = max(prod_max, num);
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ans = max(ans, prod_max);
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}
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return ans;
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}
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};
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‎minimum-window-substring/ys-han00.cpp‎

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class Solution {
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public:
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string minWindow(string s, string t) {
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int l = 0, substr = 0, min_l = 0, min_r = s.size();
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map<char, int> cnt;
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for(char c : t)
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cnt[c]++;
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for(int r = 0; r < s.size(); r++) {
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if(cnt.find(s[r]) != cnt.end()) {
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if(cnt[s[r]] > 0)
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substr++;
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cnt[s[r]]--;
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}
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while(substr == t.size()) {
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if(r - l < min_r - min_l) {
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min_l = l;
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min_r = r;
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}
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if(cnt.find(s[l]) != cnt.end()) {
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cnt[s[l]]++;
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if(cnt[s[l]] > 0)
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substr--;
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}
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l++;
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}
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}
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string ans = (min_r < s.size() ? s.substr(min_l, min_r - min_l + 1) : "");
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return ans;
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}
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};
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‎pacific-atlantic-water-flow/ys-han00.cpp‎

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// class Solution {
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// public:
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// vector<vector<int>> pacificAtlantic(vector<vector<int>>& heights) {
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// int m = heights.size(), n = heights[0].size();
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// int dx[] = {-1, 0, 1, 0};
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// int dy[] = {0, 1, 0, -1};
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// vector<vector<int>> ans;
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// for(int i = 0; i < m; i++) {
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// for(int j = 0; j < n; j++) {
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// bool pacific = false, atlantic = false;
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// queue<pair<int, pair<int, int>>> que;
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// vector<vector<bool>> check(m, vector<bool> (n, false));
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// que.push({heights[i][j], {i, j}});
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// check[i][j] = true;
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// while(!que.empty()) {
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// int h = que.front().first;
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// int x = que.front().second.first;
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// int y = que.front().second.second;
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// que.pop();
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// for(int k = 0; k < 4; k++) {
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// int new_x = x + dx[k];
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// int new_y = y + dy[k];
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// if(new_x == -1 || new_y == -1)
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// pacific = true;
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// if(new_x == m || new_y == n)
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// atlantic = true;
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// if(-1 < new_x && new_x < m && -1 < new_y && new_y < n && check[new_x][new_y] == false && heights[new_x][new_y] <= h) {
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// que.push({heights[new_x][new_y], {new_x, new_y}});
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// check[new_x][new_y] = true;
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// }
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// }
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// if(pacific && atlantic)
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// break;
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// }
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// if(pacific && atlantic)
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// ans.push_back(vector<int> {i, j});
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// }
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// }
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// return ans;
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// }
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// };
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class Solution {
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public:
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vector<vector<int>> pacificAtlantic(vector<vector<int>>& heights) {
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int dx[] = {-1, 0, 1, 0};
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int dy[] = {0, 1, 0, -1};
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int m = heights.size(), n = heights[0].size();
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vector<vector<bool>> atlantic(m, vector<bool> (n, false)), pacific(m, vector<bool> (n, false));
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queue<pair<int, int>> que;
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for(int i = 0; i < m; i++) {
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que.push({i, 0});
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pacific[i][0] = true;
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}
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for(int i = 1; i < n; i++) {
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que.push({0, i});
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pacific[0][i] = true;
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}
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while(!que.empty()) {
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int x = que.front().first;
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int y = que.front().second;
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que.pop();
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for(int i = 0; i < 4; i++) {
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int nx = x + dx[i];
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int ny = y + dy[i];
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if(nx < 0 || nx == m || ny < 0 || ny == n)
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continue;
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if(heights[x][y] <= heights[nx][ny] && !pacific[nx][ny]) {
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pacific[nx][ny] = true;
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que.push({nx, ny});
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}
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}
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}
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for(int i = 0; i < m; i++) {
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que.push({i, n - 1});
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atlantic[i][n - 1] = true;
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}
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for(int i = 0; i < n - 1; i++) {
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que.push({m - 1, i});
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atlantic[m - 1][i] = true;
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}
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while(!que.empty()) {
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int x = que.front().first;
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int y = que.front().second;
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que.pop();
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for(int i = 0; i < 4; i++) {
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int nx = x + dx[i];
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int ny = y + dy[i];
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if(nx < 0 || nx == m || ny < 0 || ny == n)
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continue;
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if(heights[x][y] <= heights[nx][ny] && !atlantic[nx][ny]) {
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atlantic[nx][ny] = true;
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que.push({nx, ny});
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}
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}
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}
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vector<vector<int>> ans;
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for(int i = 0; i < m; i++)
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for(int j = 0; j < n; j++)
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if(pacific[i][j] && atlantic[i][j])
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ans.push_back({i, j});
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return ans;
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}
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};
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‎sum-of-two-integers/ys-han00.cpp‎

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class Solution {
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public:
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int getSum(int a, int b) {
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while(b) {
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int t = a ^ b;
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b = (a & b) << 1;
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a = t;
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}
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return a;
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}
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};
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