50064. Merge Sort
難度：3/5
要記得要怎麼用fread。1
fread(dest_ptr(array), sizeof(a_block), cnt, fp);
會回傳讀到的bytes，所以如果要檢測EOF:1
2
3if(fread(ptr, sizeof(), cnt, fp) != cnt){
// EOF
}
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41#include <stdio.h>
#include <stdlib.h>
#include <limits.h>
int n;
int arr[16];
FILE* fp[16];
int have_num[16];
int cnt = 0;
int main(){
scanf("%d", &n);
for(int i = 0; i < n; i++){
char s[20]; scanf("%s", s);
fp[i] = fopen(s, "rb");
}
for(int i = 0; i < n; i++){
if(fread(&arr[i], sizeof(int), 1, fp[i]) == 1){
have_num[i] = 1, cnt++;
}
else{
have_num[i] = 0;
}
}
while(cnt != 0){
int min_idx = -1, min_num = INT_MAX;
for(int i = 0; i < n; i++){
if(have_num[i] && arr[i] < min_num){
min_idx = i;
min_num = arr[i];
}
}
printf("%d\n", arr[min_idx]);
if(fread(&arr[min_idx], sizeof(int), 1, fp[min_idx]) != 1){
have_num[min_idx] = 0, cnt--;
}
}
}