题目
Given an array nums with n integers, your task is to check if it could become non-decreasing by modifying at most one element.
We define an array is non-decreasing if nums[i] <= nums[i + 1] holds for every i (0-based) such that (0 <= i <= n - 2).
Example 1:
Input: nums = [4,2,3]
Output: true
Explanation: You could modify the first 4 to 1 to get a non-decreasing array.
Example 2:
Input: nums = [4,2,1]
Output: false
Explanation: You can’t get a non-decreasing array by modify at most one element.
Constraints:
- n == nums.length
- 1 <= n <= 10^4
- -10^5 <= nums[i] <= 10^5
代码
class Solution {
public:
bool checkPossibility(vector<int>& nums) {
if (nums.size() <= 2)
return true;
int count = 0;
for (int i = 0; i < nums.size() - 1; i++)
{
if (i == 0)
{
if (nums[i] > nums[i+1])
{
count++;
}
}
else
{
if (nums[i] > nums[i+1])
{
if (i+1 == nums.size() - 1)
count++;
else if (nums[i-1] <= nums[i+1] || nums[i] <= nums[i+2])
count++;
else
return false;
}
}
if (count > 1)
return false;
}
return true;
}
};