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].
自己琢磨的 :(简直无法忍受)
class Solution {
public boolean checkPossibility(int[] nums) {
if(nums.length<=1){
return true;
}
List<Integer> list = new ArrayList<>();
for(int i = 0;i<nums.length-1;i++){
if(nums[i]>nums[i+1]){
list.add(i+1);
}
}
if(list.size()>1){
return false;
}
if(list.size()== 0 || list.get(0)==1 || list.get(0)==nums.length-1){
return true;
}
int left =0;
for(int i = 0;i<list.get(0);i++){
if(nums[i]>nums[list.get(0)]){
left++;
}
}
int right = 0;
for (int i = list.get(0); i < nums.length; i++) {
if(nums[i]<nums[list.get(0)-1]){
right++;
}
}
if(left >1 && right>1){
return false;
}
return true;
}
}大佬的答案:
class Solution {
public boolean checkPossibility(int[] nums) {
int count = 0;
for(int i = 0;i<nums.length -1 ;i++){
if(nums[i]>nums[i+1]){
count++;
if(i>0 && nums[i+1]<nums[i-1]){
nums[i+1] = nums[i];
}
}
}
return count<=1;
}
}