Subarray Sum Equal K

LeetcodeProblems/Subarray_Sum_Equals_K.js

@@ -0,0 +1,71 @@
+
+/*
+Subarray Sum Equals K
+https://leetcode.com/problems/subarray-sum-equals-k/
+
+Given an array of integers and an integer k, you need to find the total number of continuous subarrays whose sum equals to k.
+
+Example 1:
+Input:nums = [1,1,1], k = 2
+Output: 2
+Note:
+The length of the array is in range [1, 20,000].
+The range of numbers in the array is [-1000, 1000] and the range of the integer k is [-1e7, 1e7].
+*/
+
+
+/**
+ * @param {number[]} nums
+ * @param {number} k
+ * @return {number}
+ */
+
+ // Solution 1
+var subarraySum = function(nums, k) {
+  var ret = 0;
+  for(var i = 0; i < nums.length; i++) {
+    var count = 0;
+    for(var j = i; j < nums.length; j++) {
+      count += nums[j];
+      if(count === k)
+        ret++;
+    }
+  }
+
+  return ret;
+};
+
+
+// Solution 2
+var subarraySum2 = function(nums, k) {
+  if(nums.length === 0)
+    return 0;
+
+  var sums = [];
+  sums[0] = 0;
+  var count = 0;
+  for(var i = 0; i < nums.length; i++) {
+    count += nums[i];
+    sums[i + 1] = count;
+  }
+
+  var ret = 0; 
+  for(var i = 0; i < sums.length - 1; i++) {
+    for(var j = i + 1; j < sums.length; j++) {
+      if(sums[j] - sums[i] === k)
+        ret++;
+    }
+  }
+
+  return ret;
+};
+
+var main = function() {
+  console.log(subarraySum([1,1,1], 2));
+  console.log(subarraySum([1], 0));
+  console.log(subarraySum([0], 0));
+  console.log(subarraySum([0,0,0,0,0], 0));
+}
+
+module.exports.main = main;
+

README.md

@@ -12,6 +12,7 @@ Solutions of algorithm problems using Javascript
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+| [Subarray Sum Equals K ](/LeetcodeProblems/Subarray_Sum_Equals_K.js)                                 | Medium | https://leetcode.com/problems/subarray-sum-equals-k/ | 
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