7.18

Author: zhangzhengxian

README.md

@@ -42,6 +42,9 @@
 |48|[Rotate Image](https://leetcode.com/problems/rotate-image/)| [JavaScript](./algorithms/RotateImage.js)|Medium|
 |49|[Group Anagrams](https://leetcode.com/problems/group-anagrams/)| [JavaScript](./algorithms/groupAnagrams.js)|Medium|
 |50|[Pow(x, n)](https://leetcode.com/problems/powx-n/)| [JavaScript](./algorithms/Pow(x%2C%20n).js)|Medium|
+|51|[N-Queens](https://leetcode.com/problems/n-queens/)| [JavaScript](./algorithms/N-Queens.js)|Hard|
+|53|[Maximum Subarray](https://leetcode.com/problems/maximum-subarray/)| [JavaScript](./algorithms/MaximumSubarray.js)|Easy|
+|54|[Spiral Matrix](https://leetcode.com/problems/spiral-matrix/)| [JavaScript](./algorithms/SpiralMatrix.js)|Medium|
 |69|[Sqrt(x)](https://leetcode.com/problems/sqrtx/)| [JavaScript](./algorithms/Sqrt(x).js)|Easy|
 |371|[Sum of Two Integers](https://leetcode.com/problems/sum-of-two-integers/)| [JavaScript](./algorithms/Sum_of_Two_Integers.js)|Easy|
 |372|[Super Pow](https://leetcode.com/problems/super-pow/)| [JavaScript](./algorithms/SuperPow.js)|Medium|

algorithms/MaximumSubarray.js

@@ -0,0 +1,22 @@
+/**
+ * @param {number[]} nums
+ * @return {number}
+ */
+var maxSubArray = function(nums) {
+    var temp = nums[0],
+        max = nums[0];
+    for (let i = 1; i < nums.length; i++) {
+        if (temp < 0) {
+            temp = nums[i];
+            if (nums[i] > max) {
+                max = nums[i];
+            }
+        } else {
+            if (temp + nums[i] > max) {
+                max = temp + nums[i];
+            }
+            temp = temp + nums[i];
+        }
+    }
+    return max;
+};

algorithms/N-Queens.js

@@ -0,0 +1,45 @@
+/**
+ * @param {number} n
+ * @return {string[][]}
+ */
+var solveNQueens = function(n) {
+    let result = [],
+        i = 1,
+        temp = [],
+        // 检测是否符合要求的工具函数
+        check = function(arr, num) {
+            for (let k = 0; k < num; k++) {
+                if (arr[k] === arr[num] || Math.abs(arr[k] - arr[num]) === num - k) {
+                    return false;
+                }
+            }
+            return true;
+        },
+        queens = '.'.repeat(n).split('');
+    temp[0] = 0;
+    // 回溯法求解
+    while (i > 0) {
+        temp[i - 1] += 1;
+        while (temp[i - 1] <= n){
+            if(check(temp, i - 1)) {
+                if (i === n) {
+                   result.push(temp.slice(0, n));
+                }
+                temp[i] = 0;
+                i += 2;
+                break;
+            } else {
+                temp[i - 1] += 1;
+            }
+        } 
+        i--;
+    }
+    // 得到的实际上是数字解，比如[2,4,1,3]这种，所以需要转换一下
+    return result.map((val) => {
+        return val.map((item) => {
+            let q = [...queens];
+            q.splice(item - 1, 1, 'Q');
+            return q.join('');
+        })
+    })
+};

algorithms/SpiralMatrix.js

@@ -0,0 +1,39 @@
+/**
+ * @param {number[][]} matrix
+ * @return {number[]}
+ */
+var spiralOrder = function(matrix) {
+    if (matrix.length === 0) {
+        return matrix;
+    }
+    let m = matrix.length,
+        n = matrix[0].length,
+        result =[],
+        res = [];
+    if (m === 1) {
+        return matrix[0];
+    } else if (n === 1) {
+        return matrix.map(val => {
+            return val[0];
+        })
+    }
+    let min = Math.min(m, n);
+    let count = Math.ceil(min / 2)
+    for (let i = 0; i < count; i++) {
+        let top = matrix[i].slice(i, n - i),
+            bottom = [],
+            right = [],
+            left = [];
+        if(i !== m - i - 1) {
+            bottom = matrix[m - i - 1].slice(i, n - i).reverse();
+        }
+        for (let j = i + 1; j < m - i - 1; j++) {
+            right.push(matrix[j][n - i - 1]);
+            if (i !== n - i - 1) {
+                left.push(matrix[j][i]);
+            }
+        }
+        result.push(...[...top, ...right, ...bottom, ...left.reverse()]);
+    }
+    return result;
+};