add: Sort Colors

Author: hijiangtao

README.md

@@ -25,6 +25,7 @@ This is the solutions collection of my LeetCode submissions, most of them are pr
 |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|
+|75|[Sort Colors](https://leetcode.com/problems/sort-colors/) | [JavaScript](./src/sort-colors/res.js)|Medium|
 |136|[Single Number](https://leetcode.com/problems/single-number/) | [JavaScript](./src/single-number/res.js)|Easy|
 |175|[Combine Two Tables](https://leetcode.com/problems/combine-two-tables/)| [SQL](./src/combine-two-tables/res.txt)|Easy|
 |176|[Second Highest Salary](https://leetcode.com/problems/second-highest-salary/)| [SQL](./src/second-highest-salary/res.txt)|Easy|

src/sort-colors/res.js

@@ -1,7 +1,90 @@
 /**
+ * Given an array with n objects colored red, white or blue, sort them so that objects of the same color are adjacent, with
+ * 
+ * Here, we will use the integers 0, 1, and 2 to represent the color red, white, and blue respectively.
+ * 
+ * Note:
+ * You are not suppose to use the library's sort function for this problem.
+ * 
+ * Follow up:
+ * A rather straight forward solution is a two-pass algorithm using counting sort.
+ * 
+ * First, iterate the array counting number of 0's, 1's, and 2's, then overwrite array with total number of 0's, then 1's and followed by 2's.
+ * 
+ * Could you come up with an one-pass algorithm using only constant space?
+ * 
  * res.js
  * @authors Joe Jiang ([email protected])
  * @date    2017-03-02 23:33:12
  * @version $Id$
+ * 
+ * @param {number[]} nums
+ * @return {void} Do not return anything, modify nums in-place instead.
  */
+let sortColors = function(nums) {
+   let numsize = nums.length,
+       begin = 0,
+       end = numsize-1;
+ 
+   for (let i=0; i<=end; i++) {
+       let currentVal = nums[i];
+       switch (currentVal) {
+           case 0:
+               nums[i] = nums[begin];
+               nums[begin++] = 0;
+               break;
+           case 2:
+               nums[i--] = nums[end];
+               nums[end--] = 2;
+               break;
+           default:
+               break;
+       }
+   }
+   
+};
 
+// another one-pass solution 
+let sortColors = function(nums) {
+    let numsize = nums.length, 
+    	n0 = -1, 
+    	n1 = -1, 
+    	n2 = -1;
+
+    for (let i = 0; i < numsize; ++i) {
+        if (nums[i] == 0) {
+            nums[++n2] = 2; 
+            nums[++n1] = 1; 
+            nums[++n0] = 0;
+        } else if (nums[i] == 1) {
+            nums[++n2] = 2; 
+            nums[++n1] = 1;
+        } else if (nums[i] == 2) {
+            nums[++n2] = 2;
+        }
+    }
+};
+
+// traditional two-pass solution
+let sortColors = function(nums) {
+    let numsize = nums.length,
+    	n0 = 0,
+    	n1 = 0;
+
+    for (let i = 0; i < numsize; i++) {
+        if (nums[i] === 0) {
+            nums[n0++] = 0;
+        } else if (nums[i] === 1) {
+            n1 += 1;
+        }
+    }
+
+    n1 += n0;
+    for (let i = n0; i < numsize; i++) {
+    	if (i<n1) {
+    		nums[i] = 1;
+    	} else {
+    		nums[i] = 2;
+    	}
+    }
+};