3 Sum closest

Author: ignacio-chiazzo

16 3Sum Closest.js

@@ -7,7 +7,7 @@ var threeSumClosest = function(nums, target) {
     if(nums === null || nums.length < 2){
         return null;
     }
-    
+
     if(nums.length === 3){
         return nums.reduce(function(prev,cur){return prev + cur;});
     }
@@ -16,34 +16,64 @@ var threeSumClosest = function(nums, target) {
     var closest = Infinity;
 
     nums.sort(function(a,b){return a > b ? 1 : -1;});
-    
+
     for(var i = 0; i < nums.length; i++){
         var j = i + 1;
         var k = nums.length - 1;
         while(j < k){
             var sum = nums[j] + nums[k] + nums[i];
             var diff = sum - target;
-            
+
             if(diff === 0){
                 return sum;
             }
-            
+
             if(sum < target){
                 diff = target - sum;
                 j++;
             } else {
                 diff = sum - target;
                 k--
             }
-            
+
             if(diff < closest){
                 closest = diff;
                 result = sum;
             }
         }
-        
+
         while(i < (nums.length-1) && nums[i] === nums[i+1]) i++;
     }
-    
+
     return result;
-};
+};
+
+//Shorter solution
+var threeSumClosest = function(nums, target) {
+    var closest = Number.Infinity;
+    var gap = -1;
+
+    nums.sort(function(a, b) { return a - b });
+    for(var i = 0; i < nums.length - 2; i++) {
+        var low = i + 1;
+        var high = nums.length - 1;
+
+        while(low < high) {
+            var sum = nums[i] + nums[low] + nums[high];
+            partialGap = Math.abs(target - sum);
+            if(partialGap < gap || gap === -1) {
+                gap = partialGap;
+                closest = sum;
+            }
+
+            if(sum === target) {
+                return target;
+            } else if (sum < target) {
+                low++;
+            } else {
+                high--;
+            }
+        }
+    }
+    return closest;
+};