剑指OFFER----面试题53

链接：https://leetcode-cn.com/problems/zai-pai-xu-shu-zu-zhong-cha-zhao-shu-zi-lcof/

代码

class Solution {
public:
    int search(vector<int>& nums, int target) {
        if (nums.empty()) return 0;
        int n = nums.size() - 1;

        int l = 0, r = n;
        while (l < r) {
            int mid = l + r >> 1;
            if (nums[mid] < target) l = mid + 1;
            else r = mid;
        }

        int left = l;
        l = 0, r = n;
        while (l < r) {
            int mid = l + r + 1 >> 1;
            if (nums[mid] <= target) l = mid;
            else r = mid - 1;
        }
        return r - left + 1;
    }
};