add: Spiral Matrix

Author: hijiangtao

README.md

@@ -22,6 +22,7 @@ This is the solutions collection of my LeetCode submissions, most of them are pr
 |33|[Search in Rotated Sorted Array](https://leetcode.com/problems/search-in-rotated-sorted-array/) | [JavaScript](./src/search-in-rotated-sorted-array/res.js)|Medium|
 |34|[Search for a Range](https://leetcode.com/problems/search-for-a-range/) | [JavaScript](./src/search-for-a-range/res.js)|Medium|
 |48|[Rotate Image](https://leetcode.com/problems/rotate-image/) | [JavaScript](./src/rotate-image/res.js)|Medium|
+|54|[Spiral Matrix](https://leetcode.com/problems/spiral-matrix/) | [JavaScript](./src/spiral-matrix/res.js)|Medium|
 |66|[Plus One](https://leetcode.com/problems/plus-one/) | [JavaScript](./src/plus-one/res.js)|Easy|
 |69|[Sqrt(x)](https://leetcode.com/problems/sqrtx/) | [JavaScript](./src/sqrtx/res.js)|Easy|
 |73|[Set Matrix Zeroes](https://leetcode.com/problems/set-matrix-zeroes/) | [JavaScript](./src/set-matrix-zeroes/res.js)|Medium|

src/spiral-matrix/res.js

@@ -0,0 +1,73 @@
+/**
+ * Given a matrix of m x n elements (m rows, n columns), return all elements of the matrix in spiral order.
+ * 
+ * For example,
+ * 
+ * Given the following matrix:
+ * [
+ *  [ 1, 2, 3 ],
+ *  [ 4, 5, 6 ],
+ *  [ 7, 8, 9 ]
+ * ]
+ * 
+ * You should return [1,2,3,6,9,8,7,4,5].
+ * 
+ * res.js
+ * @authors Joe Jiang (hijiangtao@gmail.com)
+ * @date    2017-03-03 21:42:58
+ * @version $Id$
+ * 
+ * @param {number[][]} matrix
+ * @return {number[]}
+ */
+let spiralOrder = function(matrix) {
+    if (matrix.length === 0) {
+        return matrix;
+    }
+    
+    let rowBegin = 0,
+        rowEnd = matrix.length-1,
+        colBegin = 0,
+        colEnd = matrix[0].length-1,
+        res =[];
+    
+    while (rowBegin <= rowEnd || colBegin <= colEnd) {
+        // left->right
+        for (let i=colBegin; i<=colEnd; i++) {
+            res.push( matrix[rowBegin][i] );
+        }
+        if (rowBegin === rowEnd) {
+            break;
+        }
+        
+        // right->bottom
+        rowBegin++;
+        for (let i=rowBegin; i<=rowEnd; i++) {
+            res.push( matrix[i][colEnd] );
+        }
+        if (colBegin === colEnd) {
+            break;
+        }
+        
+        // bottom->left
+        colEnd--;
+        for (let i=colEnd; i>=colBegin; i--) {
+            res.push( matrix[rowEnd][i] );
+        }
+        if (rowBegin === rowEnd) {
+            break;
+        }
+        
+        // left bottom->top
+        rowEnd--;
+        for (let i=rowEnd; i>=rowBegin; i--) {
+            res.push( matrix[i][colBegin] );
+        }
+        if (colBegin === colEnd) {
+            break;
+        }
+        colBegin++;
+    }
+    
+    return res;
+};