solve 217.contains-duplicate

Author: andavid

vscode/217.contains-duplicate.java

@@ -0,0 +1,50 @@
+/*
+ * @lc app=leetcode id=217 lang=java
+ *
+ * [217] Contains Duplicate
+ *
+ * https://leetcode.com/problems/contains-duplicate/description/
+ *
+ * algorithms
+ * Easy (50.84%)
+ * Total Accepted:    322K
+ * Total Submissions: 625.4K
+ * Testcase Example:  '[1,2,3,1]'
+ *
+ * Given an array of integers, find if the array contains any duplicates.
+ *
+ * Your function should return true if any value appears at least twice in the
+ * array, and it should return false if every element is distinct.
+ *
+ * Example 1:
+ *
+ *
+ * Input: [1,2,3,1]
+ * Output: true
+ *
+ * Example 2:
+ *
+ *
+ * Input: [1,2,3,4]
+ * Output: false
+ *
+ * Example 3:
+ *
+ *
+ * Input: [1,1,1,3,3,4,3,2,4,2]
+ * Output: true
+ *
+ */
+class Solution {
+  public boolean containsDuplicate(int[] nums) {
+    Set<Integer> set = new HashSet<Integer>();
+    for (int num : nums) {
+      if (set.contains(num)) {
+        return true;
+      }
+      set.add(num);
+    }
+    return false;
+  }
+}
+