1846. Maximum Element After Decreasing and Rearranging

You are given an array of positive integers arr. Perform some operations (possibly none) on arr so that it satisfies these conditions:

• The value of the first element in arr must be 1.
• The absolute difference between any 2 adjacent elements must be less than or equal to 1. In other words, abs(arr[i] - arr[i - 1]) <= 1 for each i where 1 <= i < arr.length (0-indexed). abs(x) is the absolute value of x.

There are 2 types of operations that you can perform any number of times:

• Decrease the value of any element of arr to a smaller positive integer.
• Rearrange the elements of arr to be in any order.

Return the maximum possible value of an element in arr after performing the operations to satisfy the conditions.

class Solution {
public:
    int maximumElementAfterDecrementingAndRearranging(vector<int>& A) {
        sort(begin(A), end(A));
        int res = 1;
        for(auto& a : A) {
            if(a < res) continue;
            else if(a >= res) res += 1;
        }
        
        return res - 1;
    }
};