Leetcode: Sort colors

Description:

Given an array with n objects colored red, white or blue, sort them 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.

Idea: use counting sort. First, traverse the array and calculate the numbers N0, N1, and N2 respectively. Then, the N0 0, N1 1, and N2 2 are respectively written to the original array.

Code:

void Solution::sortColors(int A[], int n){    int zero = 0;    int one = 0;    int two = 0;    int i;    for(i = 0;i < n;i++)    {        if(A[i] == 0)            zero++;        else if(A[i] == 1)            one++;        else if(A[i] == 2)            two++;    }    i = 0;    while(zero > 0)    {        A[i] = 0;        i++;        zero--;    }    while(one > 0)    {        A[i] = 1;        i++;        one--;    }    while(two > 0)    {        A[i] = 2;        i++;        two--;    }}

Leetcode: Sort colors