[[EVD]] - 剑指 Offer 53 - I. 在排序数组中查找数字 I

题目分析:[[EVD]] - 剑指 Offer 53 - I. 在排序数组中查找数字 Ihttps://leetcode-cn.com/problems/zai-pai-xu-shu-zu-zhong-cha-zhao-shu-zi-lcof/

简单描述:

• 统计target在排序数组中出现的次数

限制🚫

• 0 <= nums.length <= 10^5
• 10^9 <= nums[i] <= 10^9
• nums 是一个非递减数组
• -10^9 <= target <= 10^9

示例:

解题思路:

思路:

• #二分查找 在有序数组中,二分查找target,确定左右边界,right-left+1计算得出

效率:

• 时间复杂度
• 空间复杂度

代码:

class Solution
{
public:
    /*二分查找*/
    int search(vector<int> &nums, int target)
    {
        int left = 0, right = nums.size() - 1;
        while (left <= right)
        {
            int mid = left + (right - left) / 2;
            if (nums[mid] < target)
                left = mid + 1;
            else if (nums[mid] > target)
                right = mid - 1;
            else
            {
                while (nums[left] != target)
                    left++;
                while (nums[right] != target)
                    right--;
                break;
            }
        }
        return right - left + 1;
    }
};