Sort Colors

Author: ishpreet-singh

11.cpp

@@ -0,0 +1,38 @@
+/*
+
+Sort Colors
+-----------
+
+Solution
+Given an array with n objects colored red, white or blue, sort them in-place so that objects of the same color are adjacent, with the colors in the order red, white and blue.
+
+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.
+
+Example:
+
+Input: [2,0,2,1,1,0]
+Output: [0,0,1,1,2,2]
+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 a one-pass algorithm using only constant space?
+*/
+
+class Solution {
+public:
+    void sortColors(vector<int>& nums) {
+        int start = 0, mid = 0, end = nums.size() - 1;
+        while(mid <= end) {
+            if(nums[mid] == 0) {
+                swap(nums[start++], nums[mid++]);
+            } else if(nums[mid] == 1) {
+                mid++;
+            } else {
+                swap(nums[mid], nums[end--]);
+            }
+        }
+    }
+};

README.md

@@ -11,4 +11,5 @@
 |   7  |          Coin Change 2         |  [Link](https://github.com/ishpreet-singh/leetcode-june-challenge/blob/master/7.cpp) |
 |   8  |          Power of Two          |  [Link](https://github.com/ishpreet-singh/leetcode-june-challenge/blob/master/8.cpp) |
 |   9  |         Is Subsequence         |  [Link](https://github.com/ishpreet-singh/leetcode-june-challenge/blob/master/9.cpp) |
-|  10  |     Search Insert Position     | [Link](https://github.com/ishpreet-singh/leetcode-june-challenge/blob/master/10.cpp) |
+|  10  |     Search Insert Position     | [Link](https://github.com/ishpreet-singh/leetcode-june-challenge/blob/master/10.cpp) |
+|  11  |           Sort Colors          | [Link](https://github.com/ishpreet-singh/leetcode-june-challenge/blob/master/11.cpp) |