add 136 solution[js]

Author: limbowandering

solution/136.Single Number/Solution.js

@@ -0,0 +1,26 @@
+const singleNumber2 = function(nums){
+  const map = {};
+  for(let i = 0; i < nums.length; i++){
+    if(map[nums[i]] === undefined){
+      map[nums[i]] = 1;
+    }else if(map[nums[i]] === 1){
+      map[nums[i]]++;
+    }
+  }
+  for(let key in map){
+    if(map[key] === 1){
+      return Number(key);
+    }
+  }
+}
+const singleNumber = function(nums){
+  //XOR
+  let result = 0;
+  for(let i = 0; i < nums.length; i++){
+    result = result ^ nums[i];
+  }
+  return result;
+
+  //or in es6
+  //return nums.reduce((result, num) => result ^ num, 0);
+}