1909-RemoveOneElementToMakeTheArrayStrictlyIncreasing.go

package main

// 1909. Remove One Element to Make the Array Strictly Increasing
// 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

import "fmt"

func canBeIncreasing(nums []int) bool {
    flag := false
    for i := 1; i < len(nums); i++ {
        if nums[i] <= nums[i - 1] { // 只允许出现一次 
            if flag { return false }
            if i == 1 || nums[i] > nums[i-2] {
                nums[i-1] = nums[i]
            } else {
                nums[i] = nums[i-1]
            }
            flag = true
        }
    }
    return true
}

func main() {
    // 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.
    fmt.Println(canBeIncreasing([]int{1,2,10,5,7})) // 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.
    fmt.Println(canBeIncreasing([]int{2,3,1,2})) // 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.
    fmt.Println(canBeIncreasing([]int{1,1,1})) // false
}