#include <stdio.h>
#include <stdlib.h>
int binary_search(int a[],int n,int x){
int ret = -1;
int lef,mid,rig;
lef = 0;
rig = n-1;
while(lef <= rig){
mid = (lef + rig) /2;
//printf("%d %d %d :%d\n",lef,mid,rig,a[mid]);
if(a[mid] == x) {
ret = mid;
break;
}
if(x < a[mid]) rig = mid-1;
else lef = mid+1;
}
return ret;
}
int main(void) {
int n,x,i;
int *a;
int ans = -1;
a
= (int*)malloc(sizeof(int)*n
); if(a==NULL){
return -1;
}
for(i=0;i<n;i++){
}
ans = binary_search(a,n,x);
if(ans
!= -1) printf("a[%d] = %d\n",ans
,a
[ans
]); return 0;
}
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