HDU : 1009 (FatMouse’ Trade)



// http://acm.hdu.edu.cn/showproblem.php?pid=1009
// Runtime: 31ms
// Tag: greedy 

/* 
 * File:   main.cpp
 * Author: shahab
 * Created on March 18, 2011, 10:16 AM
 */

// @BEGIN_OF_SOURCE_CODE

#include <iostream>
#include <cstdio>
#include <algorithm>
#include <cstring>
#include <string>
#include <cctype>
#include <stack>
#include <queue>
#include <list>
#include <vector>
#include <map>
#include <sstream>
#include <cmath>
#include <bitset>
#include <utility>
#include <set>
#include <numeric>

#define INF_MAX 2147483647
#define INF_MIN -2147483647
#define pi acos(-1.0)
#define N 1000000
#define LL long long

#define For(i, a, b) for ( int i = (a); i < (b); i++ )
#define Fors(i, sz) for ( size_t i = 0; i < sz.size (); i++ )
#define Set(a, s) memset (a, s, sizeof (a))

using namespace std;

struct deal {
    int javaBean;
    int catFood;
    double unit;
} a [1000 + 5];

bool cmp (deal A, deal B)
{
    if ( A.unit > B.unit ) return true;
    return false;
}

int main(int argc, char** argv) {
    int m, n;

    while ( scanf ("%d %d", &m, &n) ) {
        if ( m == -1 && n == -1 ) break;

        for ( int i = 0; i < n; i++ ) {
            scanf ("%d %d", &a [i].javaBean, &a [i].catFood);
            if (a [i].catFood != 0 ) a [i].unit = (double)a [i].javaBean / (double)a [i].catFood;
            else a [i].unit = INF_MAX;
        }

        sort (a, a + n, cmp);
        double ret = 0;

        for ( int i = 0; i < n; i++ ) {
            if ( m >= a [i].catFood ) { ret += a [i].javaBean; m -= a [i].catFood; }
            else if ( m > 0 ) { ret += (m * a [i].unit); break; }
        }

        printf ("%.3lf\n", ret);

    }

    return 0;
}

// @END_OF_SOURCE_CODE

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s