Improved tasks 15, 20, 23

Author: javadev

src/main/js/g0001_0100/s0015_3sum/solution.js

@@ -10,14 +10,12 @@ var threeSum = function (nums) {
     nums.sort((a, b) => a - b)
     const len = nums.length
     const result = []
-
-    for (let i = 0; i < len - 2; i++) {
+    let i = 0;
+    while (i < len - 2) {
         let l = i + 1
         let r = len - 1
-
         while (r > l) {
             const sum = nums[i] + nums[l] + nums[r]
-
             if (sum < 0) {
                 l++
             } else if (sum > 0) {
@@ -37,12 +35,11 @@ var threeSum = function (nums) {
                 r--
             }
         }
-
         while (i < len - 1 && nums[i + 1] === nums[i]) {
             i++
         }
+        i++
     }
-
     return result
 }
 

src/main/js/g0001_0100/s0020_valid_parentheses/solution.js

@@ -8,8 +8,7 @@
  */
 var isValid = function (s) {
     const stack = []
-    for (let i = 0; i < s.length; i++) {
-        const c = s[i]
+    for (let c of s) {
         if (c === '(' || c === '[' || c === '{') {
             stack.push(c)
         } else if (c === ')' && stack.length > 0 && stack[stack.length - 1] === '(') {
@@ -22,7 +21,6 @@ var isValid = function (s) {
             return false
         }
     }
-
     return stack.length === 0
 }
 

src/main/js/g0001_0100/s0023_merge_k_sorted_lists/solution.js

@@ -38,7 +38,6 @@ const mergeTwoLists = function(left, right) {
     if (right === null) {
         return left
     }
-
     let res;
     if (left.val <= right.val) {
         res = left
@@ -47,27 +46,18 @@ const mergeTwoLists = function(left, right) {
         res = right
         right = right.next
     }
-
     let current = res;
-    while (left !== null || right !== null) {
-        if (left === null) {
-            current.next = right
-            right = right.next
-        } else if (right === null) {
-            current.next = left
-            left = left.next
+    while (left !== null && right !== null) {
+        if (left.val <= right.val) {
+            current.next = left;
+            left = left.next;
         } else {
-            if (left.val <= right.val) {
-                current.next = left
-                left = left.next
-            } else {
-                current.next = right
-                right = right.next
-            }
+            current.next = right;
+            right = right.next;
         }
-        current = current.next
+        current = current.next;
     }
-
+    current.next = left !== null ? left : right;
     return res
 };