二分查找（学习篇）

• • 第一种[left, right]
  • 第二种[left, right)

public static int search(int[] arr,int target) {
        int l = 0;
        int r = arr.length - 1;
        while (l <= r){
            int m = (l + r) >> 1;
            if (arr[m] == target){
                return m;
            }else if (arr[m] < target){
                l = m + 1;
            }else {
                r = m - 1;
            }
        }
        return  -1;
    }

public static int search(int[] arr,int target) {
    int l = 0;
    int r = arr.length ;
    while (l < r){
        int m = (l + r) >> 1;
        if (arr[m] == target){
            return m;
        }else if (arr[m] < target){
            l = m + 1;
        }else {
            r = m;
        }
    }
    return  -1;
}