HDU 1160 FatMouse's Speed（最长递减子序列变形）

题目地址：点击打开链接

题意：给一堆老鼠，求一个最大的子集，子集的特点是从开头到结尾重量严格递增，速度严格递减

思路：先给所有老鼠按重量递增排个序，然后对速度求最长递减子序列

AC代码：

#include <iostream>
#include <cstring>
#include <cstdio>
#include <cstdlib>
#include <algorithm>

using namespace std;

int dp[1001],pre[1001];

struct mouse
{
    int weight,speed,num;
}mou[1001];

int cmp(const void *_a,const void *_b)
{
    mouse *a = (mouse*)_a;
    mouse *b = (mouse*)_b;
    if(a->weight != b->weight)
        return a->weight - b->weight;
    return b->speed - a->speed;
}

void output(int i)
{
    if(i == 0)
        return;
    output(pre[i]);
    printf("%d\n",mou[i].num);
}

int main()
{
    int i,j,n = 1,max = 0,l;
    while(scanf("%d%d",&mou[n].weight,&mou[n].speed) != EOF)
    {
        mou[n].num = n;
        n++;
    }
    memset(dp,0,sizeof(dp));
    memset(pre,0,sizeof(pre));
    qsort(mou+1,n-1,sizeof(mouse),cmp);
    dp[1] = 1;
    for(i=2; i<=n; i++)
    {
        for(j=1; j<i; j++)
        {
            if(mou[i].weight > mou[j].weight && mou[i].speed < mou[j].speed && dp[i] < dp[j])//要严格递增，所以要再比较一次
            {
                dp[i] = dp[j];
                pre[i] = j;
            }
        }
        dp[i]++;
    }
    for(i=1; i<=n; i++)
    {
        if(dp[i] > max)
        {
            l = i;
            max = dp[i];
        }
    }
    printf("%d\n",max);
    output(l);
    return 0;
}