add: Partition Equal Subset Sum

Author: hijiangtao

README.md

@@ -54,6 +54,7 @@ This is the solutions collection of my LeetCode submissions, most of them are pr
 |371|[Sum of Two Integers](https://leetcode.com/problems/sum-of-two-integers/) | [JavaScript](./src/sum-of-two-integers/res.js)|Easy|
 |384|[Shuffle an Array](https://leetcode.com/problems/shuffle-an-array/) | [JavaScript](./src/shuffle-an-array/res.js)|Medium|
 |404|[Sum of Left Leaves](https://leetcode.com/problems/sum-of-left-leaves/) | [JavaScript](./src/sum-of-left-leaves/res.js)|Easy|
+|416|[Partition Equal Subset Sum](https://leetcode.com/problems/partition-equal-subset-sum/) | [JavaScript](./src/partition-equal-subset-sum/res.js)|Medium|
 |434|[Number of Segments in a String](https://leetcode.com/problems/number-of-segments-in-a-string/) | [JavaScript](./src/number-of-segments-in-a-string/res.js)|Easy|
 |516|[Longest Palindromic Subsequence](https://leetcode.com/problems/longest-palindromic-subsequence/) | [JavaScript](./src/longest-palindromic-subsequence/res.js)|Medium|
 |523|[Continuous Subarray Sum](https://leetcode.com/problems/continuous-subarray-sum/) | [JavaScript](./src/continuous-subarray-sum/res.js)|Medium|

src/partition-equal-subset-sum/res.js

@@ -0,0 +1,45 @@
+/**
+ * res.js
+ * @authors Joe Jiang (hijiangtao@gmail.com)
+ * @date    2017-04-12 21:44:08
+ * 
+ * Given a non-empty array containing only positive integers, find if the array can be partitioned into two subsets such that the sum of elements in both subsets is equal.
+ * 
+ * Note:
+ * Each of the array element will not exceed 100
+ * The array size will not exceed 200.
+ *
+ * Optimize Idea: https://discuss.leetcode.com/topic/67539/0-1-knapsack-detailed-explanation/2
+ * 
+ * @param {number[]} nums
+ * @return {boolean}
+ */
+let canPartition = function(nums) {
+	let len = nums.length,
+		res = 0;
+	if (len === 1) return false;
+
+	// 求和
+	for (let i = 0; i < len; i++) {
+		res += nums[i];
+	}
+	if (res % 2) return false;
+	res /= 2;
+
+	// 初始化结果数组,所有元素初始化为0
+	let arr = new Array(res + 1);
+	arr[0] = 1;
+	for (let i = 1; i <= res; i++) {
+		arr[i] = 0;
+	}
+
+	// 遍历 nums 数组更新 arr
+	for (let i = 0; i < len; i++) {
+		for (let j = res; j >= nums[i]; j--) {
+			arr[j] += arr[j - nums[i]];
+		}
+		if (arr[res]) return true;
+	}
+
+	return false;
+};