Solution Week11: missing-number

Author: juhui-jeong

missing-number/juhui-jeong.java

@@ -0,0 +1,31 @@
+/*
+ * 시간 복잡도: O(n)
+ * 공간 복잡도: O(1)
+ */
+class Solution {
+    public int missingNumber(int[] nums) {
+        int n = nums.length;
+        long expected = n * (n + 1) / 2;
+        long actual = 0;
+        for (int x : nums) {
+            actual += x;
+        }
+        return (int) (expected - actual);
+    }
+}
+
+/*
+ * 시간 복잡도: O(n log n)
+ * 공간 복잡도: O(1)
+ */
+class Solution {
+    public int missingNumber(int[] nums) {
+        Arrays.sort(nums);
+        for (int i = 0; i < nums.length; i++) {
+            if (i != nums[i]) {
+                return i;
+            }
+        }
+        return nums.length;
+    }
+}