Detailed explanation: solution

```
class Solution {
public boolean checkPossibility(int[] nums) {
int l = nums.length,cnt = 0;
for(int i=0;i<l-1 && cnt<=1;++i){
if(nums[i]>nums[i+1]){ //e.g. [2,2,3,2,4] 3>2
if(i>0){
if(nums[i-1]<=nums[i+1]) //if number is lesser or equal modify nums[i]
nums[i] = nums[i-1]; // to the previous number. 2<=2 modify nums[i] =2
else //in all other cases modify the next number
nums[i+1] = nums[i]; //to the current number to match the sequence
}
++cnt;
}
}
return cnt<=1;
}
}
```