README.md

Non-decreasing Array

Description

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].

Tags: Array

思路

题目要求判断所给数组能否能通过最多一次的修改，变为递增数组。

Java:

public boolean checkPossibility(int[] nums) {
    if (nums.length < 3) {
        return true;
    }

    int modifyCount = 0;

    if (nums[0] > nums[1]) {
        modifyCount++;
        nums[0] = nums[1];
    }

    for (int i = 1; i < nums.length && modifyCount < 2; i++) {
        if (nums[i] < nums[i-1]) {
            if (nums[i] > nums[i-2]) {
                nums[i-1] = nums[i-2];
            } else {
                nums[i] = nums[i-1];
            }
            modifyCount++;
        }
    }
    return modifyCount < 2;
}

结语

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