single number ii

Author: chen0040

.idea/workspace.xml

@@ -388,3 +388,4 @@ codes may not be optimized
 1. [Find Duplicate Subtrees](https://leetcode.com/problems/find-duplicate-subtrees/description/)
 1. [Longest Absolute File Path](https://leetcode.com/problems/longest-absolute-file-path/description/)
 1. [Maximum Product of Word Length](https://leetcode.com/problems/maximum-product-of-word-lengths/description/)
+1. [Single Number II](https://leetcode.com/problems/single-number-ii/description/)

README.md

@@ -0,0 +1,37 @@
+package com.github.chen0040.leetcode.day18.medium;
+
+
+import java.util.HashMap;
+import java.util.Map;
+
+
+/**
+ * Created by xschen on 13/8/2017.
+ *
+ * link: https://leetcode.com/problems/single-number-ii/description/
+ */
+public class SingleNumberII {
+   public class Solution {
+      public int singleNumber(int[] nums) {
+         Map<Integer, Integer> counts = new HashMap<Integer, Integer>();
+         for(int i=0; i < nums.length; ++i) {
+            int num = nums[i];
+            if(counts.containsKey(num)) {
+               int count = counts.get(num) - 1;
+               if(count == 0) {
+                  counts.remove(num);
+               } else {
+                  counts.put(num, count);
+               }
+            } else {
+               counts.put(num, 2);
+            }
+         }
+
+         for(Integer num : counts.keySet()) {
+            return num;
+         }
+         return -1;
+      }
+   }
+}