75. Sort Colors

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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?

 my code:

class Solution {public:    void sortColors(vector<int>& nums) {        int len = nums.size();        for (int i = 1; i <= len; ++i) {            for (int j = i-1; j > 0; --j) {                if (nums[j] < nums[j-1]) {                    int con = nums[j];                    nums[j] = nums[j-1];                    nums[j-1] = con;                }            }        }    }};

Runtime: 0 ms, faster than 100.00% of C++ online submissions for Sort Colors.

 

 

 

75. Sort Colors