题目描述(Medium)
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.
题目链接
https://leetcode.com/problems/first-missing-positive/description/
Example 1:
Input: [2,0,2,1,1,0]
Output: [0,0,1,1,2,2]
算法分析
由于只有三种颜色,可以设置两个index,一个是red的index,一个是blue的index,两边往中间走。
提交代码:
class Solution {
public:
void sortColors(vector<int>& nums) {
int red = 0, blue = nums.size() - 1;
for (int i = 0; i < blue + 1; )
{
if (nums[i] == 0)
swap(nums[i++], nums[red++]);
else if (nums[i] == 2)
swap(nums[i], nums[blue--]);
else
++i;
}
}
};