class Solution {
    public boolean checkPossibility(int[] nums) {
        int count = 0;
        for (int i = 1; i < nums.length; i++) {
            if (nums[i - 1] > nums[i]) {
                count++;
                if (count > 1) {
                    return false;
                }
                if (i < 2 || nums[i - 2] <= nums[i]) {
                    //if decrease nums[i - 1] is safe, then decrease it is always a good choice
                    //nums[i] >= nums[i - 2] makes decrease nums[i - 1] a safe choice
                    nums[i - 1] = nums[i];
                } else {
                    nums[i] = nums[i - 1];
                }
            }
        }
        return true;
    }
}