[]算法]二分查找

测试

 

 

 

 

 

 

 

 

 

 原本10次的循环优化成了4次

源代码
public static void main(String[] args) {
    int target = 9;
    int[] nums = new int[]{-1, 0, 3, 5, 9, 12, 20, 21, 22, 23,25};
    int search = search(nums, target);
    System.out.println(search);
}

public static int search(int[] nums, int target) {
    int left = 0, right = nums.length - 1;
    while (left <= right) {
        int mid = (right + left) / 2;
        int num = nums[mid];
        if (num == target) {
            return mid;
        } else if (num > target) {
            right = mid - 1;
        } else {
            left = mid + 1;
        }
    }
    return -1;
}