HDU 1160 FatMouse's Speed (sort + dp)

题目链接：http://acm.hdu.edu.cn/showproblem.php?pid=1160

给你一些老鼠的体重和速度，问你最多需要几只可以证明体重越重速度越慢，并输出任意一组答案。

结构体按照体重从小到大排序，然后根据速度就是最长下降子序列。

//#pragma comment(linker, "/STACK:102400000, 102400000")
#include <algorithm>
#include <iostream>
#include <cstdlib>
#include <cstring>
#include <cstdio>
#include <vector>
#include <cmath>
#include <ctime>
#include <list>
#include <set>
#include <map>
using namespace std;
typedef long long LL;
typedef pair <int, int> P;
const int N = 1105;
struct Mouse {
    int fat, run, id;
    bool operator <(const Mouse& cmp) const {
        if(fat == cmp.fat)
            return run > cmp.run;
        return fat < cmp.fat;
    }
}a[N];
int dp[N];
int pre[N], ans[N];

int main()
{
    int f = 1;
    while(scanf("%d %d", &a[f].fat, &a[f].run) != EOF) {
        a[f].id = f;
        f++;
    }   
    for(int i = 0; i <= f; ++i) {
        pre[i] = i;
    }
    sort(a + 1, a + f);
    memset(dp, 0, sizeof(dp));
    int Max = 1, pos = 1;
    for(int i = 1; i < f; ++i) {
        dp[i] = 1;
        for(int j = 1; j < i; ++j) {
            if(a[i].fat > a[j].fat && a[i].run < a[j].run) {
                if(dp[j] + 1 > dp[i]) {
                    pre[a[i].id] = a[j].id;
                    dp[i] = dp[j] + 1;
                }
            }
        }
        if(dp[i] > Max) {
            pos = a[i].id;
            Max = dp[i];
        }
    }
    printf("%d
", Max);
    int i = pos, cnt = 0;
    for(i = pos; i != pre[i]; i = pre[i]) {
        ans[++cnt] = i;
    }
    ans[++cnt] = i;
    for(i = cnt; i >= 1; --i) {
        printf("%d
", ans[i]);
    }
    return 0;
}