OJ刷题记录：L1-205-携带硬币去购物(15分)

#include <iostream>
#include <vector>
#include <algorithm>

using namespace std;

int main() {
	int max, n, value;
	vector<int> coin;
	
	cin >> max >> n;
	
	for (int i = 0; i < n; i++) {
		cin >> value;
		coin.emplace_back(value);
	}
	sort(coin.begin(), coin.end());
	
	if (coin[0] != 1) {
		cout << -1;
		return 0;
	}
	
	//
	int sum = 1, ans = 1; 
	while (max > sum){
   		for (int i = n - 1; i >= 0; i--){
            if (coin[i] <= sum + 1) {     
                ans++;           
                sum += coin[i];    
                break;
            }
        }
    }
	//
	
	cout << ans;
	
	return 0;
}