665. Non-decreasing Array

Given an array with n integers, your task is to check if it could become non-decreasing by modifying at most 1 element.

We define an array is non-decreasing if array[i] <= array[i + 1] holds for every i (1 <= i < n).

Example 1:

Input: [4,2,3]
Output: True
Explanation: You could modify the first 4 to 1 to get a non-decreasing array.

 

Example 2:

Input: [4,2,1]
Output: False
Explanation: You can't get a non-decreasing array by modify at most one element.

 

Note: The n belongs to [1, 10,000].

 

 

思路：

1，遍历一遍，把每个数换成相邻的 数，再检查这个数列是不是递减的数组

 

#pragma once

#include<iostream>
#include<vector>

using namespace std;

class Solution {
public:
	bool checkPossibility(vector<int>& nums) {
		//如果小于等于2位数则肯定可以

		if (nums.size() <= 2)
		{
			return true;
		}
		int t = 0;
		for (int i = 0; i < nums.size() ; i++)
		{
			vector <int> temp = nums;
			//每次循环时把当前的数替换为相邻的数
			if (i == nums.size()-1)
			{
				temp[i] = temp[i - 1];
			}
			else if(i==0){
				temp[i] = nums[i + 1];

			}
			//检查替换后的数组是不是递减的
			for (int j = 0; j < temp.size() - 1; j++)
			{
				if (temp[j] > temp[j + 1])
				{
					t++;

				}
			}

			if (t == 0)
			{
				return true;
			}
			t = 0;
		}

		return false;

	}
};