contains duplicate

Author: Grit03

contains-duplicate/Grit03.js

@@ -0,0 +1,22 @@
+/**
+ * @param {number[]} nums
+ * @return {boolean}
+ */
+var containsDuplicate = function (nums) {
+  const countMap = new Map();
+
+  for (let i = 0; i < nums.length; i++) {
+    const key = nums[i];
+    if (countMap.has(key)) {
+      const value = countMap.get(key);
+      if (value === 1) {
+        return true;
+      }
+      countMap.set(key, value + 1);
+    } else {
+      countMap.set(key, 1);
+    }
+  }
+
+  return false;
+};