add js solution to leetcode problem: no.18

Author: 0xtch

solution/0000-0099/0018.4Sum/README.md

@@ -132,6 +132,47 @@ class Solution {
 }
 ```
 
+### **JavaScript**
+```js
+/**
+ * @param {number[]} nums
+ * @param {number} target
+ * @return {number[][]}
+ */
+var fourSum = function (nums, target) {
+    let len = nums.length;
+    let res = [];
+    if (len < 4) return [];
+    nums.sort((a, b) => a - b);
+    for (i = 0; i < len - 3; i++) {
+        if (i > 0 && nums[i] === nums[i - 1]) continue;
+        if (nums[i] + nums[len - 1] + nums[len - 2] + nums[len - 3] < target) continue;
+        if (nums[i] + nums[i + 1] + nums[i + 2] + nums[i + 3] > target) break;
+        for (j = i + 1; j < len - 2; j++) {
+            if (j > i + 1 && nums[j] === nums[j - 1]) continue;
+            let left = j + 1, right = len - 1;
+            while (left < right) {
+                if (nums[i] + nums[j] + nums[left] + nums[right] === target) {
+                    res.push([nums[i], nums[j], nums[left], nums[right]]);
+                    while (nums[left] === nums[left + 1]) left++;
+                    left++;
+                    while (nums[right] === nums[right - 1]) right--;
+                    right--;
+                    continue;
+                } else if (nums[i] + nums[j] + nums[left] + nums[right] > target) {
+                    right--;
+                    continue;
+                } else {
+                    left++;
+                    continue;
+                }
+            }
+        }
+    }
+    return res;
+};
+```
+
 ### **...**
 
 ```

solution/0000-0099/0018.4Sum/README_EN.md

@@ -125,6 +125,46 @@ class Solution {
     }
 }
 ```
+### **JavaScript**
+```js
+/**
+ * @param {number[]} nums
+ * @param {number} target
+ * @return {number[][]}
+ */
+var fourSum = function (nums, target) {
+    let len = nums.length;
+    let res = [];
+    if (len < 4) return [];
+    nums.sort((a, b) => a - b);
+    for (i = 0; i < len - 3; i++) {
+        if (i > 0 && nums[i] === nums[i - 1]) continue;
+        if (nums[i] + nums[len - 1] + nums[len - 2] + nums[len - 3] < target) continue;
+        if (nums[i] + nums[i + 1] + nums[i + 2] + nums[i + 3] > target) break;
+        for (j = i + 1; j < len - 2; j++) {
+            if (j > i + 1 && nums[j] === nums[j - 1]) continue;
+            let left = j + 1, right = len - 1;
+            while (left < right) {
+                if (nums[i] + nums[j] + nums[left] + nums[right] === target) {
+                    res.push([nums[i], nums[j], nums[left], nums[right]]);
+                    while (nums[left] === nums[left + 1]) left++;
+                    left++;
+                    while (nums[right] === nums[right - 1]) right--;
+                    right--;
+                    continue;
+                } else if (nums[i] + nums[j] + nums[left] + nums[right] > target) {
+                    right--;
+                    continue;
+                } else {
+                    left++;
+                    continue;
+                }
+            }
+        }
+    }
+    return res;
+};
+```
 
 ### **...**
 

solution/0000-0099/0018.4Sum/Solution.js

@@ -0,0 +1,37 @@
+/**
+ * @param {number[]} nums
+ * @param {number} target
+ * @return {number[][]}
+ */
+var fourSum = function (nums, target) {
+    let len = nums.length;
+    let res = [];
+    if (len < 4) return [];
+    nums.sort((a, b) => a - b);
+    for (i = 0; i < len - 3; i++) {
+        if (i > 0 && nums[i] === nums[i - 1]) continue;
+        if (nums[i] + nums[len - 1] + nums[len - 2] + nums[len - 3] < target) continue;
+        if (nums[i] + nums[i + 1] + nums[i + 2] + nums[i + 3] > target) break;
+        for (j = i + 1; j < len - 2; j++) {
+            if (j > i + 1 && nums[j] === nums[j - 1]) continue;
+            let left = j + 1, right = len - 1;
+            while (left < right) {
+                if (nums[i] + nums[j] + nums[left] + nums[right] === target) {
+                    res.push([nums[i], nums[j], nums[left], nums[right]]);
+                    while (nums[left] === nums[left + 1]) left++;
+                    left++;
+                    while (nums[right] === nums[right - 1]) right--;
+                    right--;
+                    continue;
+                } else if (nums[i] + nums[j] + nums[left] + nums[right] > target) {
+                    right--;
+                    continue;
+                } else {
+                    left++;
+                    continue;
+                }
+            }
+        }
+    }
+    return res;
+};