Java之折半查询（二分法）

//普通折半查询
public static int binarySearch(int num, int[] arr) {
int min, mid, max;
min = 0;
max = arr.length - 1;
while (min <= max) {
mid = (min + max) / 2;
if (arr[mid] == num) {
return mid + 1;
} else if (num > arr[mid]) {
min = mid + 1;
} else {
max = mid - 1;
}
}
return -1;
}

//递归折半查询
public static int binarySearchByRecursion(int num, int[] arr, int min, int max) {
int mid;
if (min <= max) {
mid = (min + max) / 2;
if (arr[mid] == num) {
return mid + 1;
} else if (num > arr[mid]) {
return binarySearchByRecursion(num, arr, mid + 1, max);
} else {
return binarySearchByRecursion(num, arr, min, mid - 1);
}
}
return -1;
}