包子凑数（蓝桥杯17H）————动态规划+二分查找

#include<iostream>
using namespace std;
int gcd(int a,int b) {
	int tmp;
	if (a<b) {
		tmp = a;
		a = b;
		b = tmp;
	}
	return b == 0 ? a : gcd(b,a%b);
}
int main() {
	int dp[10001],n;
	memset(dp,0,sizeof(dp));
	cin >> n;
	int* a = new int[n];
	int g,maxn = 0;
	for (int i = 0; i < n;i++) {
		cin >> a[i];
		if (i == 0) {
			g = a[i];
		}
		else {
			g = gcd(g,a[i]);
		}
		maxn = max(maxn, a[i]);
	}
	if (g != 1) {
		cout << "INF";
		return 1;
	}
	dp[0] = 1;
	for (int i = 0; i < n;i++) {
		for (int j = a[i]; j < 10001;j++) {
			dp[j] = (dp[j]>0||dp[j-a[i]]>0)?1:0;
		}
	}
	for (int i = 10001/2; i>0;i/=2) {
		int cnt = 0;
		for (int j = i; j > i - maxn;j--) {
			if (dp[j] == 1) {
				cnt++;
			}
		}
		if (cnt != maxn) {
			int ans = 0;
			for (int z = 1; z <= i * 2;z++) {
				if (!dp[z]) {
					ans++;
				}
			}
			cout << ans;
			return 0;
		}
	}
	return 0;
}