HDOJ 1160 FatMouse's Speed

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

typedef struct s_mouse{
int id;
int weight;
int speed;
}s_mouse;

static s_mouse mice[1000];
static int m[1000];
static int s[1000];
//static int p[1000];

static int num;

int m_compare(const void *a,const void *b)
{
s_mouse *a_m=(s_mouse *)a;
s_mouse *b_m=(s_mouse *)b;
if(a_m->weight == b_m->weight
&&	a_m->speed == b_m->speed)
return 0;
if(a_m->weight < b_m->weight
|| a_m->weight == b_m->weight && a_m->speed > b_m->speed)
return -1;
return 1;
}

static void fat_mouse()
{
//1. sort
qsort(mice,num,sizeof(s_mouse),m_compare);

//2. Dynamic Programming
//2.1 initialize
m[num-1]=1;
s[num-1]=0;
//2.2 scan
int i,j;
for(i=num-2;i>=0;i--){
int max=1;
int maxi=0;
for(j=num-1;j>i;j--){
if(mice[i].weight<mice[j].weight &&
mice[i].speed>mice[j].speed){
if(max<m[j]+1){
max=m[j]+1;
maxi=j;
}
}
}
m[i]=max;
s[i]=maxi;
}
}

int main(int argc,char *argv[])
{
int i;
for(i=0;scanf("%d%d",&mice[i].weight,&mice[i].speed)>0;i++)
mice[i].id=i+1;
num=i;
fat_mouse();
int max_index=0;
for(i=num-1;i>0;i--)
if(m[i]>m[max_index])
max_index=i;
printf("%d\n",m[max_index]);
for(i=max_index;s[i]!=0;){
printf("%d\n",mice[i].id);
i=s[i];
}
printf("%d\n",mice[i].id);
return 0;
}