二分查找

int Search_Binary(int a[], int n, int key){

	int low = 0;
	int high = n - 1;

	while(low <= high){

		int mid = (low + high) / 2;

		if(key == a[mid])
			return mid;
		else if(key > a[mid])
			low = mid + 1;
		else
			high = mid - 1;
	}

	return 0;
}