Recently your team noticed that the computer you use to practice for programming contests is notgood enough anymore. Therefore, you decide to buy a new computer.
To make the ideal computer for your needs, you decide to buy separate components and assemblethe computer yourself. You need to buy exactly one of each type of component.
The problem is which components to buy. As you all know, the quality of a computer is equal tothe quality of its weakest component. Therefore, you want to maximize the quality of the componentwith the lowest quality, while not exceeding your budget.分析：最小值最大问题，用二分。
#include <cstdio>
#include <vector>
#include <string>
#include <map>
#include <algorithm>
using namespace std;
const int N = 1000 + 5;
map<string,int> id;
int cnt,n, b; //组件的类型数、数目、预算
struct Component{
int price, quality;
Component(int a,int b): price(a), quality(b){}
};
vector<Component> comp[N];
int ID(const string &s){
if(!id.count(s)){
return id[s] = cnt++;
}
return id[s];
}
bool ok(int q){
int sum = 0;
for(int i = 0; i < cnt; i++){
int cheapest = b+1, len = comp[i].size();
for(int j = 0; j < len; j++) //找到符合条件的component
if(q <= comp[i][j].quality) cheapest = min(cheapest, comp[i][j].price);
if(cheapest == b+1) return false; //找不到 >= q的组件
sum += cheapest;
if(sum > b) return false;
}
return true;
}
int main(int argc, char** argv) {
int t;
scanf("%d",&t);
while(t--){
scanf("%d%d",&n,&b);
cnt = 0;
int maxq = 0;
id.clear();
while(n--){
char type[25],name[25];
int p, q;
scanf("%s%s%d%d",&type,name,&p,&q);
comp[ID(type)].push_back(Component(p,q));
maxq = max(maxq, q);
}
int L = 0, R = maxq;
while(L < R){
int M = L + (R - L + 1)/2;
//不+1，可能存在，M = L 无限循环；其实也可以用<= L作为循环条件，L = M+1,但是效率没有这个高
if(ok(M)) L = M;
else R = M-1;
}
printf("%d\n",L);
for(int i = 0; i < cnt; i++) comp[i].clear();
}
return 0;
}Input
On the rst line one positive number: the number of testcases, at most 100. After that per testcase:
• One line with two integers: 1 n 1000, the number of available components and 1 b 1000000000, your budget.
• n lines in the following format: `type name price quality', where type is a string with the typeof the component, name is a string with the unique name of the component, price is an integer(0 price 1000000) which represents the price of the component and quality is an integer(0 quality 1000000000) which represents the quality of the component (higher is better). Thestrings contain only letters, digits and underscores and have a maximal length of 20 characters.
It will always possible to construct a computer with your budget.
Output
Per testcase:
• One line with one integer: the maximal possible quality.
Sample Input
1
18 800
processor 3500_MHz 66 5
processor 4200_MHz 103 7
processor 5000_MHz 156 9
processor 6000_MHz 219 12
memory 1_GB 35 3
memory 2_GB 88 6
memory 4_GB 170 12
mainbord all_onboard 52 10
harddisk 250_GB 54 10
harddisk 500_FB 99 12
casing midi 36 10
monitor 17_inch 157 5
monitor 19_inch 175 7
monitor 20_inch 210 9
monitor 22_inch 293 12
mouse cordless_optical 18 12
mouse microsoft 30 9
keyboard office 4 10
Sample Output
9