pku1065 Wooden Sticks

http://poj.org/problem?id=1065

DP，最长“上升”子序列

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

struct Sticks
{
    int x, y;
}s[5432];

int n, dp[5432];

int cmp1(struct Sticks a, struct Sticks b)
{
    return a.x < b.x || a.y < b.y;
}

int LIS()
{
    int i, j, max1, max2 = 1;
    dp[0] = 1;
    for(i=1; i<n; i++)
    {
        max1 = 0;
        for(j=0; j<i; j++)
        {
            if(cmp1(s[i], s[j]) && dp[j]>max1)
            {
                max1 = dp[j];
            }
        }
        dp[i] = max1+1;
        if(dp[i] > max2)
        {
            max2 = dp[i];
        }
    }
    return max2;
}

int cmp(const void *a, const void *b)
{
    struct Sticks p, q;
    p = *(struct Sticks *)a;
    q = *(struct Sticks *)b;
    return (q.x < p.x || (p.x==q.x && q.y<p.y))? 1: -1;
}

int main()
{
    int t, i;
    scanf("%d", &t);
    while(t-- && scanf("%d", &n))
    {
        for(i=0; i<n; i++)
        {
            scanf("%d%d", &s[i].x, &s[i].y);
        }
        qsort(s, n, sizeof(s[0]), cmp);
        printf("%d\n", LIS());
    }
    return 0;
}