#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 i,j=0,ret = -1;
	for(i=0;i<n;i++){
		if(a[i]==x){
			return j;
		}
		j=j+1;
	}
		return ret;
}
 
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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

MTIgNQoxIDIgMyA0IDUgOCA5IDEzIDE2IDIxIDI1IDI3

12 5
1 2 3 4 5 8 9 13 16 21 25 27