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75-颜色分类

LeetCode

发布日期: 2021-10-26

LeetCode 75. Sort Colors

Given an array nums 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.

We will use the integers 0, 1, and 2 to represent the color red, white, and blue, respectively.

You must solve this problem without using the library’s sort function.

Example 1:

Input: nums = [2,0,2,1,1,0]
Output: [0,0,1,1,2,2]

method

让zero, one, two分别为0,1,2的末尾指针，遍历数组

如果是0，则zero++, one++, two++
如果是1，则one++, two++
如果是2，则two++

void sortColors(vector<int>& nums) {
    int zero = -1;
    int one = -1;
    int two = -1;
    for (int i = 0; i < nums.size(); i++) {
        if (nums[i] == 0) {
            nums[++two] = 2;
            nums[++one] = 1;
            nums[++zero] = 0;
        }
        else if (nums[i] == 1) {
            nums[++two] = 2;
            nums[++one] = 1;
        }
        else {
            nums[++two] = 2;
        }
    }
}