#include <stdio.h>
#include <stdlib.h>
//この関数を実装する
int binary_search(int a[],int n,int x){
int lef, rig, mid;
lef=0;
rig=n-1;
int ret=-1;
while(lef<=rig){
mid=(lef+rig)/2;
if(a[mid]==x){
ret=mid;
break;
}
if(x<a[mid])
rig = mid-1;
else lef = mid+1;
}
return ret;
}
//この関数の内側だけを書く
int main(void) {
int n,x,i;
int *a;
int ans = -1;
scanf("%d %d",&n,&x);
a = (int*)malloc(sizeof(int)*n);
if(a==NULL){
printf("ERROR\n");
return -1;
}
for(i=0;i<n;i++){
scanf("%d",&a[i]);
}
ans = binary_search(a,n,x);
if(ans != -1) printf("a[%d] = %d\n",ans,a[ans]);
else printf("not found\n");
free(a);
return 0;
}
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