Leetcode 剑指 Offer 53 - I. 在排序数组中查找数字 I（DAY 176）---- 二分查找学习期

浅浅的花香味﹌ 2022-09-13 04:09 108阅读 0赞

### 文章目录 ###

*   *  原题题目
     *  代码实现（首刷自解 题目很简单 自写upper lower\_bound函数）

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## 原题题目 ##

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![在这里插入图片描述][watermark_type_ZHJvaWRzYW5zZmFsbGJhY2s_shadow_50_text_Q1NETiBATG92ZSA2_size_20_color_FFFFFF_t_70_g_se_x_16]

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## 代码实现（首刷自解 题目很简单 自写upper lower\_bound函数） ##

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

[watermark_type_ZHJvaWRzYW5zZmFsbGJhY2s_shadow_50_text_Q1NETiBATG92ZSA2_size_20_color_FFFFFF_t_70_g_se_x_16]: /images/20220828/f6029af14a3d4845be3a4b75444c1c42.png