hdu1160 FatMouse's Speed

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

DP,LIS

#include <stdio.h>
#include <stdlib.h>

struct Point
{
    int x, y, num;
}p[1234];

int cmp(const void *a, const void *b)
{
    return ((struct Point *)b)->x - ((struct Point *)a)->x;
}

int n, dp[1234], pre[1234], result;

int main()
{
    int i, j, temp, flag;
    for(i=1; ~scanf("%d%d", &p[i].x, &p[i].y); i++)
    {
        p[i].num = i;
    }
    n = i-1;
    qsort(p+1, n, sizeof(p[0]), cmp);
    result = pre[1] = dp[1] = 1;
    for(i=2; i<=n; i++)
    {
        temp = 0;
        flag = i;
        for(j=1; j<i; j++)
        {
            if(p[j].y<p[i].y && p[j].x!=p[i].x && dp[j]>temp)
            {
                temp = dp[j];
                flag = j;
            }
        }
        dp[i] = temp + 1;
        pre[i] = flag;
        if(dp[i] > dp[result])
        {
            result = i;
        }
    }
    printf("%d\n", dp[result]);
    while(result != pre[result])
    {
        printf("%d\n", p[result].num);
        result = pre[result];
    }
    printf("%d\n", p[result].num);
    return 0;
}