refactor: var -> let

Author: sl1673495

BFS问题/在每个树行中找最大值-515.js

@@ -29,7 +29,7 @@
  * @param {TreeNode} root
  * @return {number[]}
  */
-var largestValues = function (root) {
+let largestValues = function (root) {
   if (!root) return [];
   let queue = [root];
   let maximums = [];
@@ -69,7 +69,7 @@ function TreeNode(val) {
 }
 
 /** 预期：[1, 3, 9] */
-var root = new TreeNode(1);
+let root = new TreeNode(1);
 root.left = new TreeNode(3);
 root.right = new TreeNode(2);
 root.left.left = new TreeNode(5);
@@ -85,7 +85,7 @@ root.right.right = new TreeNode(9);
 
  */
 /** 预期：[5, 14, 1] */
-var root2 = new TreeNode(5);
+let root2 = new TreeNode(5);
 root2.left = new TreeNode(14);
 root2.left.left = new TreeNode(1);
 

DFS问题/index.md

@@ -9,19 +9,19 @@
 这样遍历所走的路就会少很多。
 
 ```js
-var solve = function (board) {
+let solve = function (board) {
   if (board.length == 0) return null;
 
-  for (var y = 0; y < board.length; y++) {
-    for (var x = 0; x < board[0].length; x++) {
+  for (let y = 0; y < board.length; y++) {
+    for (let x = 0; x < board[0].length; x++) {
       if (board[y][x] == "O" && (y == 0 || y == board.length - 1 || x == 0 || x == board[0].length - 1)) {
         dfs(board, y, x);
       }
     }
   }
 
-  for (var y = 0; y < board.length; y++) {
-    for (var x = 0; x < board[0].length; x++) {
+  for (let y = 0; y < board.length; y++) {
+    for (let x = 0; x < board[0].length; x++) {
       if (board[y][x] == "W") {
         board[y][x] = "O";
       } else {

DFS问题/图像渲染-733.js

@@ -5,7 +5,7 @@
  * @param {number} newColor
  * @return {number[][]}
  */
-var floodFill = function (image, sr, sc, newColor) {
+let floodFill = function (image, sr, sc, newColor) {
   let current = image[sr][sc];
   dfs(image, sr, sc, current, newColor);
   return image;

DFS问题/岛屿数量.js

@@ -26,7 +26,7 @@
     链接：https://leetcode-cn.com/problems/number-of-islands
     著作权归领扣网络所有。商业转载请联系官方授权，非商业转载请注明出处。
  */
-var numIslands = function (grid) {
+let numIslands = function (grid) {
     let count = 0
     for (let i = 0; i < grid.length; i++) {
         let row = grid[i]

DFS问题/岛屿的周长-463.js

@@ -3,7 +3,7 @@
  * @param {number[][]} grid
  * @return {number}
  */
-var islandPerimeter = function (grid) {
+let islandPerimeter = function (grid) {
   let yLen = grid.length;
   if (!yLen) return 0;
   let xLen = grid[0].length;

DFS问题/岛屿的最大面积-659.js

@@ -4,7 +4,7 @@
  * @param {number[][]} grid
  * @return {number}
  */
-var maxAreaOfIsland = function (grid) {
+let maxAreaOfIsland = function (grid) {
   let yLen = grid.length;
   if (!yLen) return grid;
   let xLen = grid[0].length;

DFS问题/被围绕的区域-循环版.js

@@ -33,7 +33,7 @@ function genKey(i, j) {
   return `${i}-${j}`;
 }
 
-var solve = function (board) {
+let solve = function (board) {
   const notXMap = {};
   for (let i = 0; i < board.length; i++) {
     let row = board[i];

DFS问题/被围绕的区域-正解版.js

@@ -1,18 +1,18 @@
 // https://github.com/sl1673495/daily-plan/issues/16
 
-var solve = function (board) {
+let solve = function (board) {
   if (board.length == 0) return null;
 
-  for (var y = 0; y < board.length; y++) {
-    for (var x = 0; x < board[0].length; x++) {
+  for (let y = 0; y < board.length; y++) {
+    for (let x = 0; x < board[0].length; x++) {
       if (board[y][x] == "O" && (y == 0 || y == board.length - 1 || x == 0 || x == board[0].length - 1)) {
         dfs(board, y, x);
       }
     }
   }
 
-  for (var y = 0; y < board.length; y++) {
-    for (var x = 0; x < board[0].length; x++) {
+  for (let y = 0; y < board.length; y++) {
+    for (let x = 0; x < board[0].length; x++) {
       if (board[y][x] == "W") {
         board[y][x] = "O";
       } else {

DFS问题/被围绕的区域.js

@@ -33,7 +33,7 @@ function genKey(i, j) {
   return `${i}-${j}`;
 }
 
-var solve = function (board) {
+let solve = function (board) {
   const notXMap = {};
   for (let i = 0; i < board.length; i++) {
     let row = board[i];

sum-four-divisors.js

@@ -2,10 +2,10 @@
  * @param {number[]} nums
  * @return {number}
  */
-var sumFourDivisors = function(nums) {
-  var sum = 0
-  for (var i = 0; i < nums.length; i++) {
-      var divisorSet = findDivisor(nums[i])
+let sumFourDivisors = function(nums) {
+  let sum = 0
+  for (let i = 0; i < nums.length; i++) {
+      let divisorSet = findDivisor(nums[i])
       if (divisorSet.size === 4) {
           divisorSet.forEach(num => {
               sum += num
@@ -17,10 +17,10 @@ var sumFourDivisors = function(nums) {
 
 function findDivisor(num) {
   // 超过这个边界就不用继续求值了
-  var max = Math.floor(Math.sqrt(num))
-  var set = new Set()
-  for (var i = 1; i <= max; i ++) {
-      var result = num / i
+  let max = Math.floor(Math.sqrt(num))
+  let set = new Set()
+  for (let i = 1; i <= max; i ++) {
+      let result = num / i
       // 除数是整数
       if (result % 1 === 0) {
           set.add(result)