75. Sort Colors

class Solution {
    public void sortColors(int[] nums) {
        int r = 0;
        int b = 0;
        
        for (int i = 0; i < nums.length; i++) {
            if (nums[i] == 0) r++;
            else if (nums[i] == 2) b++;
        }
        int w = nums.length - r - b;
        
        for (int j = 0; j < nums.length; j++) {
            if (j < r) {
                nums[j] = 0;
            } else if (j < nums.length - b) {
                nums[j] = 1;
            } else {
                nums[j] = 2; 
            }
        }
    }
}

Runtime: 0 ms, faster than 100.00% of Java online submissions for Sort Colors.
Memory Usage: 37.3 MB, less than 93.93% of Java online submissions for Sort Colors.

in place는 아니지만 쉽게 풀었당

Dijkstra 를 이용하여 inplace로 풀기

class Solution {
    public void sortColors(int[] nums) {
        int l = 0;
        int cur = 0;
        int r = nums.length - 1;
        
        int tmp;
        
        while (cur <= r) {
            if (nums[cur] == 0) {
                tmp = nums[l];
                nums[l++] = nums[cur];
                nums[cur++] = tmp;
            } else if (nums[cur] == 2) {
                tmp = nums[cur];
                nums[cur] = nums[r];
                nums[r--] = tmp; 
            } else {
                cur++;
            }
        }
    }
}

Runtime: 0 ms, faster than 100.00% of Java online submissions for Sort Colors.
Memory Usage: 37.3 MB, less than 86.34% of Java online submissions for Sort Colors.