Merge pull request neetcode-gh#1899 from andynullwong/0018

Create 0018-4sum.js & .ts

javascript/0018-4sum.js

@@ -0,0 +1,48 @@
+/**
+ * @param {number[]} nums
+ * @param {number} target
+ * @return {number[][]}
+ */
+var fourSum = function (nums, target) {
+ const sortedNums = nums.sort((a, b) => a - b);
+ const res = [];
+ const quad = [];
+
+ const kSum = (k, start, target) => {
+ if (k > 2) {
+ for (let i = start; i < sortedNums.length; i++) {
+ if (i !== start && sortedNums[i] === sortedNums[i - 1]) {
+ continue;
+ }
+ quad.push(sortedNums[i]);
+ kSum(k - 1, i + 1, target - sortedNums[i]);
+ quad.pop();
+ }
+ } else {
+ let left = start;
+ let right = sortedNums.length - 1;
+
+ while (left < right) {
+ const sum = sortedNums[left] + sortedNums[right];
+ if (sum < target) {
+ left++;
+ } else if (sum > target) {
+ right--;
+ } else {
+ res.push(
+ quad.concat([sortedNums[left], sortedNums[right]])
+ );
+ left++;
+ while (
+ left < right &&
+ sortedNums[left] === sortedNums[left - 1]
+ ) {
+ left++;
+ }
+ }
+ }
+ }
+ };
+ kSum(4, 0, target);
+ return res;
+};

typescript/0018-4sum.ts

@@ -0,0 +1,43 @@
+function fourSum(nums: number[], target: number): number[][] {
+ const sortedNums: number[] = nums.sort((a: number, b: number) => a - b);
+ const res: number[][] = [];
+ const quad: number[] = [];
+
+ const kSum = (k: number, start: number, target: number): void => {
+ if (k > 2) {
+ for (let i = start; i < sortedNums.length; i++) {
+ if (i !== start && sortedNums[i] === sortedNums[i - 1]) {
+ continue;
+ }
+ quad.push(sortedNums[i]);
+ kSum(k - 1, i + 1, target - sortedNums[i]);
+ quad.pop();
+ }
+ } else {
+ let left: number = start;
+ let right: number = sortedNums.length - 1;
+
+ while (left < right) {
+ const sum = sortedNums[left] + sortedNums[right];
+ if (sum < target) {
+ left++;
+ } else if (sum > target) {
+ right--;
+ } else {
+ res.push(
+ quad.concat([sortedNums[left], sortedNums[right]])
+ );
+ left++;
+ while (
+ left < right &&
+ sortedNums[left] === sortedNums[left - 1]
+ ) {
+ left++;
+ }
+ }
+ }
+ }
+ };
+ kSum(4, 0, target);
+ return res;
+}