HDU ACM 1257 最少拦截系统 (贪心法)

http://acm.hdu.edu.cn/showproblem.php?pid=1257

 

用贪心的思想,每一个系统尽可能多的去拦截导弹.

 

#include <iostream>
#include <algorithm>
#include <stack>
using namespace std;
const int MAX = 1000 + 10;
const int INF = 0x3fffffff;
struct Mouse
{
    int fat;
    int speed;
    int num;
};
bool cmp(Mouse a,Mouse b)
{
    if(a.fat != b.fat )
    {
        return a.fat < b.fat;
    }
    else
    {
        if(a.speed != b.speed )
        {
            return a.fat > b.fat;
        }
        else
        {
            return a.num < b.num;
        }
    }
}
int main()
{
    int f,s;
    int n = 1;
    Mouse m[MAX] = {0};
    while(cin>>f>>s)
    {
        
        m[n].fat = f;
        m[n].speed = s;
        m[n].num = n;
        n++;
    }
    sort(m+1,m+n,cmp);
    int father[MAX] = {0};
    int i,j;
    int max = 0;
    int mark = 0;
    for(i=1;i<n;i++)
    {
        father[i] = 1;
        for(j=1;j<i;j++)
        {
            if(m[j].fat < m[i].fat && m[j].speed > m[i].speed && father[i] < father[j] + 1)
            {
                father[i] = father[j] + 1;
                if(father[i] > max)
                {
                    max = father[i];
                    mark = i;
                }
            }
        }
    }
    int now = max;
    cout<<max<<endl;
    stack <int> stack;
    for(i=mark;i>0;i--)
    {
        if(father[i] == now)
        {
            now--;
            stack.push(m[i].num);
        }
    }
    while(!stack.empty())
    {
        cout<<stack.top ()<<endl;
        stack.pop ();
    }
    return 0;
}