题目3A. int binarySearch(int a[], int n, int x){ if(n > 0 && x >= a[0]){ int low = 0, high = n-1;while(low < high){ int mid=(low+high+1)/2;if(x < a[mid])high=mid-1;else low=mid;}if(x==a[low]) return low;}return –1;}B. int binarySearch (int a[], int n, int x){ int low=0, high=n-1;while(low<high-1){ int mid=(low+high)/2;if(x<a[mid])high=mid;else low=mid;}if(x==a[low]) return low;else return –1;}C. int binarySearch(int a[], int n, int x){ int low=0, high=n-1;while(low+1!=high){ int mid=(low+high)/2;if(x>=a[mid]) low=mid;else high=mid;}if(x==a[low]) return low;else return –1;}D. int binarySearch(int a[], int n, int x){ int low=0, high=n-1;while(low<=high){ int mid=(low+high)/2;if(x==a[mid]) return mid;if(x>a[mid]) low=mid;else high=mid;}return –1;}