1909. Remove One Element to Make the Array Strictly Increasing

Problem

Tags: Array

Given a 0-indexed integer array nums, return true if it can be made strictly increasing after removing exactly one element, or false otherwise. If the array is already strictly increasing, return true.

The array nums is strictly increasing if nums[i - 1] < nums[i] for each index (1 <= i < nums.length).

Example 1:

Input: nums = [1,2,10,5,7]
Output: true
Explanation: By removing 10 at index 2 from nums, it becomes [1,2,5,7].
[1,2,5,7] is strictly increasing, so return true.

Example 2:

Input: nums = [2,3,1,2]
Output: false
Explanation:
[3,1,2] is the result of removing the element at index 0.
[2,1,2] is the result of removing the element at index 1.
[2,3,2] is the result of removing the element at index 2.
[2,3,1] is the result of removing the element at index 3.
No resulting array is strictly increasing, so return false.

Example 3:

Input: nums = [1,1,1]
Output: false
Explanation: The result of removing any element is [1,1].
[1,1] is not strictly increasing, so return false.

Constraints:

• 2 <= nums.length <= 1000
• 1 <= nums[i] <= 1000

Code

JS

// 1909. Remove One Element to Make the Array Strictly Increasing (5/13/53455)
// Runtime: 68 ms (68.31%) Memory: 39.05 MB (94.77%) 

/**
 * @param {number[]} nums
 * @return {boolean}
 */
var canBeIncreasing = function(nums) {
    if(nums.length === 2) return true;
    
    let fall = -1;
    for(let i = 0; i < nums.length - 1; i++) {
        if(nums[i] >= nums[i+1]) {
            if(fall === -1) fall = i;
            else return false;
        }
    }
    
    if(fall === -1) return true;
    if(fall === 0 || fall === nums.length - 2) return true;
    
    let passed = false;
    if(fall > 0) {
        if(nums[fall-1] < nums[fall+1]) passed = true;
    }
    if(!passed && fall + 2 < nums.length) {
        if(nums[fall] < nums[fall+2]) passed = true;
    }
    return passed;
};