なんか釣りっぽいんだが、不明な箇所は俺のESPで補った
#include<stdio.h>
#include <stdlib.h>
#include <time.h>

int fortune(){
int r,i=0,rate[] = {50,200,500,200};
r = 1000*rand()/RAND_MAX;
while(i<sizeof(rate)/sizeof(int)){
if((r-=rate[i])<0) break;
i++;
}
return i;
}

int main(void){
char *data[] = {"大凶","凶","吉","小吉","大吉,\"中吉"};
int i,r,count[sizeof(data)/sizeof(int)] = {0};
srand(time(NULL));
for(i=0;i<2000;++i){
count[r = fortune()]++;
printf("%s\n",data[r]);
}
for(i=0;i<sizeof(data)/sizeof(int);++i){
printf("%s %d回 %f％\n",data[i],count[i],(float)count[i]/2000);
}
return 0;
}