Merge pull request #2466 from junzero741/main

[junzero741] WEEK 04 Solutions

Author: junzero741

find-minimum-in-rotated-sorted-array/junzero741.ts

@@ -0,0 +1,18 @@
+// TC: O(logN)
+// SC: O(1)
+function findMin(nums: number[]): number {
+    let left = 0;
+    let right = nums.length - 1;
+
+    while (left < right) {
+        const mid = Math.floor((left+right)/2);
+        if(nums[mid] > nums[right]) {
+            left = mid + 1;
+        } else {
+            right = mid;
+        }
+    }
+
+    return nums[left];
+    
+};

maximum-depth-of-binary-tree/junzero741.ts

@@ -0,0 +1,38 @@
+class TreeNode {
+    val: number
+    left: TreeNode | null
+    right: TreeNode | null
+    constructor(val?: number, left?: TreeNode | null, right?: TreeNode | null) {
+        this.val = (val===undefined ? 0 : val)
+        this.left = (left===undefined ? null : left)
+        this.right = (right===undefined ? null : right)
+    }
+}
+
+// TC: O(N)
+// SC: O(N)
+function maxDepth(root: TreeNode | null): number {
+    if(!root) {
+        return 0;
+    }
+
+    let maxLv = 1;
+
+    function dfs(node: TreeNode, lv: number) {
+        if(node.left) {
+            dfs(node.left, lv+1)
+        }
+        if(node.right) {
+            dfs(node.right, lv+1)
+        }
+        maxLv = Math.max(maxLv, lv)
+    }
+
+
+    dfs(root, 1);
+    
+
+    return maxLv;
+
+    
+};

merge-two-sorted-lists/junzero741.ts

@@ -0,0 +1,30 @@
+  class ListNode {
+      val: number
+      next: ListNode | null
+      constructor(val?: number, next?: ListNode | null) {
+          this.val = (val===undefined ? 0 : val)
+          this.next = (next===undefined ? null : next)
+      }
+  }
+
+
+function mergeTwoLists(list1: ListNode | null, list2: ListNode | null): ListNode | null {
+    
+   const dummy = new ListNode();
+    let tail = dummy;
+
+    while (list1 && list2) {
+        if (list1.val <= list2.val) {
+            tail.next = list1;
+            list1 = list1.next;
+        } else {
+            tail.next = list2;
+            list2 = list2.next;
+        }
+        tail = tail.next;
+    }
+
+    tail.next = list1 || list2;
+
+    return dummy.next;
+};

word-search/junzero741.ts

@@ -0,0 +1,41 @@
+// TC: O(M*N*4^L)
+// SC: O(L) 
+function exist(board: string[][], word: string): boolean {
+    const rows = board.length;
+    const cols = board[0].length;
+
+    function dfs(r: number, c: number, index: number): boolean {
+        if (index === word.length) return true;
+
+        if (
+            r < 0 || r >= rows || 
+            c < 0 || c >= cols || 
+            board[r][c] !== word[index]
+        ) {
+            return false;
+        }
+
+        const temp = board[r][c];
+        board[r][c] = '#';
+
+        const found = 
+            dfs(r + 1, c, index + 1) ||
+            dfs(r - 1, c, index + 1) ||
+            dfs(r, c + 1, index + 1) ||
+            dfs(r, c - 1, index + 1);
+
+        board[r][c] = temp;
+
+        return found;
+    }
+
+    for (let i = 0; i < rows; i++) {
+        for (let j = 0; j < cols; j++) {
+            if (board[i][j] === word[0] && dfs(i, j, 0)) {
+                return true;
+            }
+        }
+    }
+
+    return false;
+}