Update: 0015-3sum.js

javascript/0015-3sum.js

@@ -1,52 +1,34 @@
 /**
- * https://leetcode.com/problems/3sum/
- * Time O(N ^ 2) | Space O(N)
  * @param {number[]} nums
  * @return {number[][]}
  */
-var threeSum = function (nums, sums = []) {
- nums.sort((a, b) => a - b);
-
- for (let first = 0; first < nums.length - 2; first++) {
- if (isPrevDuplicate(nums, first)) continue;
-
- const [target, left, right] = [
- -nums[first],
- first + 1,
- nums.length - 1,
- ];
-
- search(nums, target, left, right, sums);
- }
-
- return sums;
-};
-
-const isPrevDuplicate = (nums, index) => nums[index - 1] === nums[index];
-
-const isNextDuplicate = (nums, index) => nums[index] === nums[index + 1];
-
-const search = (nums, target, left, right, sums) => {
- while (left < right) {
- const [leftVal, rightVal] = [nums[left], nums[right]];
- const sum = leftVal + rightVal;
-
- const isTarget = sum === target;
- if (isTarget) {
- sums.push([-target, leftVal, rightVal]);
- left++;
- right--;
-
- while (left < right && isPrevDuplicate(nums, left)) left++;
- while (left < right && isNextDuplicate(nums, right)) right--;
-
- continue;
+var threeSum = function(nums) {
+ const res = [];
+ nums.sort((a,b) => a-b)
+
+ for (let i = 0; i < nums.length; i++) {
+ const a = nums[i];
+ if (a > 0) break;
+ if (i > 0 && a === nums[i - 1]) continue;
+
+ let l = i + 1;
+ let r = nums.length - 1;
+ while (l < r) {
+ const threeSum = a + nums[l] + nums[r];
+ if (threeSum > 0) {
+ r--;
+ } else if (threeSum < 0) {
+ l++;
+ } else {
+ res.push([a, nums[l], nums[r]]);
+ l++;
+ r--;
+ while (nums[l] === nums[l - 1] && l < r) {
+ l++;
+ }
+ }
  }
-
- const isTargetGreater = sum < target;
- if (isTargetGreater) left++;
-
- const isTargetLess = target < sum;
- if (isTargetLess) right--;
  }
-};
+ return res;
+}
+