missing number solved

Author: mintheon

missing-number/mintheon.java

@@ -0,0 +1,17 @@
+class Solution {
+  /**
+   시간복잡도: O(n)
+   공간복잡도: O(1)
+   */
+  public int missingNumber(int[] nums) {
+    int n = nums.length;
+    int expectedSum = n * (n + 1) / 2;
+
+    int arraySum = 0;
+    for(int i = 0; i < nums.length; i++) {
+      arraySum += nums[i];
+    }
+
+    return expectedSum - arraySum;
+  }
+}