//递归
public int recursionSearch(int[] arr, int key, int low, int high) {
if(key < arr[low] || key > arr[high] || low > high) {
return -1;
}int mid = (low + high) / 2;
if(key < arr[mid]) {
return recursionSearch(arr, key, low, mid - 1);
} else if(key > arr[mid]) {
return recursionSearch(arr, key, mid + 1, high);
} else {
return mid;
}
}//迭代
public int commonSearch(int[] arr, int key) {
int low = 0;
int high = arr.length - 1;
int mid = 0;
if(key < arr[low] || key > arr[high] || low > high) {
return -1;
}while(low <= high) {
mid = (low + high) / 2;
if(key < mid) {
high = mid - 1;
} else if(key > mid) {
low = mid + 1;
} else {
return mid;
}
}return -1;
}【二分查找（面试必会知识点）】
