Maximum Number of Integers to Choose From a Range I

Problem Statement - link #

You are given an integer array banned and two integers n and maxSum. You are choosing some number of integers following the below rules:

• The chosen integers have to be in the range [1, n].
• Each integer can be chosen at most once.
• The chosen integers should not be in the array banned.
• The sum of the chosen integers should not exceed maxSum.

Return the maximum number of integers you can choose following the mentioned rules.

Examples #

Example 1:

Input: banned = [1,6,5], n = 5, maxSum = 6
Output: 2
Explanation: You can choose the integers 2 and 4.
2 and 4 are from the range [1, 5], both did not appear in banned, and their sum is 6, which did not exceed maxSum.

Example 2:

Input: banned = [1,2,3,4,5,6,7], n = 8, maxSum = 1
Output: 0
Explanation: You cannot choose any integer while following the mentioned conditions.

Example 3:

Input: banned = [11], n = 7, maxSum = 50
Output: 7
Explanation: You can choose the integers 1, 2, 3, 4, 5, 6, and 7.
They are from the range [1, 7], all did not appear in banned, and their sum is 28, which did not exceed maxSum.

Constraints #

• 1 <= banned.length <= 10^4
• 1 <= banned[i], n <= 10^4
• 1 <= maxSum <= 10^9

Solutions #

class Solution {
public:
    int maxCount(vector<int>& banned, int n, int maxSum) {
        unordered_set<int> set(banned.begin(), banned.end());
        int curSum = 0;
        int res = 0;
        for(int i = 1; i <= n; i++) {
            if(set.find(i) == set.end()) {
                curSum += i;
                if( curSum <= maxSum) {
                    res += 1;
                }
                else {
                    break;
                }

            }
        }
        return res;
    }
};