Merge branch 'main' of github.com:w2xi/leetcode

Author: w2xi

README.md

@@ -32,7 +32,9 @@
 |35|[搜索插入位置](https://leetcode.cn/problems/search-insert-position/)|[JavaScript](./algorithms/search-insert-position.js)|Easy|
 |48|[旋转图像](https://leetcode.cn/problems/rotate-image/)|[JavaScript](./algorithms/rotate-image.js)|Medium|
 |49|[字母异位词分组](https://leetcode.cn/problems/group-anagrams/)|[JavaScript](./algorithms/group-anagrams.js)|Medium|
+|54|[螺旋矩阵](https://leetcode.cn/problems/spiral-matrix/)|[JavaScript](./algorithms/spiral-matrix.js)|Medium|
 |58|[最后一个单词的长度](https://leetcode.cn/problems/length-of-last-word/)|[JavaScript](./algorithms/length-of-last-word.js)|Easy|
+|59|[螺旋矩阵 II](https://leetcode.cn/problems/spiral-matrix-ii/)|[JavaScript](./algorithms/spiral-matrix-ii.js)|Medium|
 |53|[最大子数组和](https://leetcode.cn/problems/maximum-subarray/)|[JavaScript](./algorithms/maximum-subarray.js)|Easy|
 |66|[加一](https://leetcode-cn.com/problems/plus-one/)|[JavaScript](./algorithms/plus-one.js)|Easy|
 |69|[x 的平方根 ](https://leetcode.cn/problems/sqrtx/)|[JavaScript](./algorithms/sqrtx.js)|Easy|

algorithms/fruit-into-baskets.js

@@ -1,4 +1,5 @@
 /**
+ * 904. 水果成篮
  * @param {number[]} fruits
  * @return {number}
  */
@@ -11,6 +12,7 @@ var totalFruit = function (fruits) {
 
   for (let right = 0; right < fruits.length; right++) {
     const curr = fruits[right];
+    // 存储每个水果种类出现的次数
     map.set(curr, (map.get(curr) || 0) + 1);
 
     while (map.size > 2) {
@@ -22,6 +24,7 @@ var totalFruit = function (fruits) {
       }
       left++;
     }
+    // 更新最大数目
     maxLen = Math.max(maxLen, right - left + 1);
   }
 

algorithms/minimum-size-subarray-sum.js

@@ -4,7 +4,8 @@
  * @return {number}
  */
 var minSubArrayLen = function (target, nums) {
-  // 滑动窗口
+  // 滑动窗口 
+  // 时间复杂度: O(n)
 
   // 滑动窗口起始位置
   let left = 0;
@@ -19,11 +20,36 @@ var minSubArrayLen = function (target, nums) {
     while (sum >= target) {
       // 更新最小长度
       minLen = Math.min(minLen, right - left + 1);
+      // 调整区间值
       sum -= nums[left];
+      // 调整起始位置
       left++;
     }
     right++;
   }
 
   return minLen === Number.MAX_VALUE ? 0 : minLen;
 };
+
+
+/**
+ * 暴力破解
+ * 时间复杂度: O(n^2)
+ */
+function crash(target, nums) {
+  let minCount = 0;
+
+  for (let i = 0; i < nums.length; i++) {
+    let sum = 0;
+    for (let j = i; j < nums.length; j++) {
+      sum += nums[j];
+      if (sum >= target) {
+        let subLen = j - i + 1;
+        minCount = minCount ? Math.min(subLen, minCount) : subLen;
+        break;
+      }
+    }
+  }
+
+  return minCount;
+}

algorithms/move-zeroes.js

@@ -3,17 +3,31 @@
  * @return {void} Do not return anything, modify nums in-place instead.
  */
 var moveZeroes = function (nums) {
-  let index = 0;
+  // 双指针 (二刷的写法)
 
-  for (let i = 0; i < nums.length; i++) {
-    if (nums[i] !== 0) {
-      nums[index] = nums[i];
-      index++;
+  let slowIndex = 0;
+
+  for (let fastIndex = 1; fastIndex < nums.length; fastIndex++) {
+    if (nums[slowIndex] === 0) {
+      if (nums[fastIndex] !== 0) {
+        swap(nums, slowIndex++, fastIndex);
+      }
+    } else {
+      slowIndex++;
     }
   }
-  for (let i = index; i < nums.length; i++) {
-    nums[i] = 0;
-  }
+
+  // let index = 0;
+
+  // for (let i = 0; i < nums.length; i++) {
+  //   if (nums[i] !== 0) {
+  //     nums[index] = nums[i];
+  //     index++;
+  //   }
+  // }
+  // for (let i = index; i < nums.length; i++) {
+  //   nums[i] = 0;
+  // }
 
   // 双指针
 

algorithms/spiral-matrix-ii.js

@@ -0,0 +1,31 @@
+/**
+ * 59. 螺旋矩阵 II
+ * 参考: https://leetcode.cn/problems/spiral-matrix-ii/solution/spiral-matrix-ii-mo-ni-fa-she-ding-bian-jie-qing-x/
+ * @param {number} n
+ * @return {number[][]}
+ */
+var generateMatrix = function (n) {
+  let cur = 1;
+  let top = 0;
+  let bottom = n - 1;
+  let left = 0;
+  let right = n - 1;
+  const tar = n * n;
+
+  const mat = Array(n)
+    .fill(0)
+    .map(() => Array(n).fill(0));
+
+  while (cur <= tar) {
+    for (let i = left; i <= right; i++) mat[top][i] = cur++;
+    top++;
+    for (let i = top; i <= bottom; i++) mat[i][right] = cur++;
+    right--;
+    for (let i = right; i >= left; i--) mat[bottom][i] = cur++;
+    bottom--;
+    for (let i = bottom; i >= top; i--) mat[i][left] = cur++;
+    left++;
+  }
+
+  return mat;
+};

algorithms/spiral-matrix.js

@@ -0,0 +1,37 @@
+/**
+ * 54. 螺旋矩阵
+ * 参考: https://leetcode.cn/problems/spiral-matrix/solution/cxiang-xi-ti-jie-by-youlookdeliciousc-3/
+ * @param {number[][]} matrix
+ * @return {number[]}
+ */
+var spiralOrder = function (matrix) {
+  if (matrix.length === 0) return [];
+
+  // 赋值上下左右边界
+  let left = 0,
+    top = 0;
+  let right = matrix[0].length - 1;
+  let bottom = matrix.length - 1;
+  let result = [];
+
+  while (true) {
+    // 从左到右
+    for (let i = left; i <= right; i++) result.push(matrix[top][i]);
+    // 重新设定上边界. 若上边界大于下边界，则遍历完成，下同
+    if (++top > bottom) break;
+
+    // 从上到下
+    for (let i = top; i <= bottom; i++) result.push(matrix[i][right]);
+    if (--right < left) break;
+
+    // 从右到左
+    for (let i = right; i >= left; i--) result.push(matrix[bottom][i]);
+    if (--bottom < top) break;
+
+    // 从下到上
+    for (let i = bottom; i >= top; i--) result.push(matrix[i][left]);
+    if (++left > right) break;
+  }
+
+  return result;
+};

algorithms/squares-of-a-sorted-array.js

@@ -4,15 +4,16 @@
  * @return {number[]}
  */
 var sortedSquares = function (nums) {
-  let i = 0,
-    j = nums.length - 1;
   let result = Array(nums.length).fill(0);
-  let count = nums.length - 1;
+  let i = 0;
+  let j = nums.length - 1;
+  // 标记 result 数组需要填充的索引值 ( 从后往前 )
+  let count = j;
 
   while (i <= j) {
     const left = Math.abs(nums[i]);
     const right = Math.abs(nums[j]);
-
+    // 比较绝对值大小
     if (right > left) {
       result[count--] = right * right;
       j--;