UVALive 3971 Assemble 电脑配件 二分+贪心

题意:某人想组装电脑,有很多电脑配件可以选,每样都有它的价格和质量,每种配件一定要买一个,现在给出钱数,求能组装出来的电脑里面配件质量最便宜的是多少。当然不能超出预算的啦。

每次枚举那个最便宜的,然后贪心,每次找价格最小且价格大于最便宜的,如果超支就向前二分,否则向后二分。

这题折腾了一晚上 = =,差点跪了。。。最后发现排序没处理好,郁闷。。。得先排前再排质量。

代码:

/*
*  Author:      illuz <iilluzen[at]gmail.com>
*  Blog:        http://blog.csdn.net/hcbbt
*  File:        l3971.cpp
*  Create Date: 2013-09-09 21:14:09
*  Descripton:  binary, greedy 
*/

#include <cstdio>
#include <vector>
#include <iostream>
#include <map>
#include <set>
#include <algorithm>
using namespace std;

const int MAXN = 1000;

struct P {
	string nam;
	int mon;
	int qua;
	friend bool operator < (const P &a, const P &b) {
		if (a.mon != b.mon)
			return a.mon < b.mon;
		return a.qua > b.qua; 
	}
	P() {}
	P(string s, int m, int q) {
		nam = s;
		mon = m;
		qua = q;
	}
};
int n, b, cnt;
set<P> v[MAXN];
map<string, int> app;

bool judge(int m) {
	int sum = 0;
	for (int i = 1; i < cnt; i++) {
		bool choose = false;
		for (set<P>::iterator j = v[i].begin(); j != v[i].end(); j++) {
			if ((*j).qua >= m) {
				//				cout << sum << ' ';
				choose = true;
				sum += (*j).mon;
				break;
			}
		}
		if (false == choose || sum > b)
			return false;
	}
	return true;
}

int main() {
	int t;
	string tmp;
	scanf("%d", &t);
	while (t--) {
		scanf("%d%d", &n, &b);
		int tm, tq;
		int L = 0, R = 0, mid;
		app.clear();
		for (int i = 1; i < cnt; i++)
			v[i].clear();
		cnt = 1;
		for (int i = 0; i < n; i++) {
			cin >> tmp;
			scanf("%*s%d%d", &tm, &tq);
			R = max(R, tq);
			if (app[tmp] == 0) {
				app[tmp] = cnt;
				v[cnt++].insert(P(tmp, tm, tq));
			}
			else
				v[app[tmp]].insert(P(tmp, tm, tq));
		}
		while (L < R) {
			mid = L + (R - L) / 2;
			if (L == mid) break;
			if (judge(mid)) L = mid;
			else R = mid;
			//	cout << "\n!!!!!!!!!!!!" << mid << endl;
		}
		if (judge(mid + 1)) mid++;
		printf("%d\n", mid);
	}
	return 0;
}


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