LeetCode开心刷题十八天——34. Find First and Last Position of Element in Sorted ArrayEasy

ATTENTION:only thing need to pay attention is the loop condition is left<=right,don;t forget =

PROBLEM：my code is long,there must some easier way to design it

34. Find First and Last Position of Element in Sorted Array

Medium

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Given an array of integers nums sorted in ascending order,find the starting and ending position of a given target value.

Your algorithm‘s runtime complexity must be in the order of O(log n).

If the target is not found in the array,return [-1,-1].

Example 1:

Input: nums = [,target = 8
Output: [3,4]5,7,8,10]

Example 2:

Input: nums = [,target = 6
Output: [-1,-1]

Answer Code:5,10]

#include<stdio.h>
#include<iostream>
#include<vector>
#include<algorithm>
#include<stack>
#include<string>

using namespace std;
class Solution {
public:
    vector<int> searchRange(vector<int>& nums,int target) {
        int n=nums.size();
        cout<<"n:"<<n<<endl;
        vector<int> res;
        if(n==1)
        {
            if(target==nums[0])
            {
                res.push_back(0);
                res.push_back(0);
                return res;
            }
            else
            {
                res.push_back(-1);
                res.push_back(-1);
                return res;
            }
        }
        int left=0,right=n-1;
        int flag=0,mid=0;
        while(left<=right)
        {
            mid=(left+right)/2;
            cout<<"mid:"<<mid<<endl;
            if(nums[mid]==target)
            {
                flag=1;
                break;
            }
            if(nums[mid]>target)
            {
                right=mid-1;
            }
            else if(nums[mid]<target)
            {
                left=mid+1;
                //cout<<"left:"<<left<<endl;
            }
        }
        if(flag==0)
        {
            res.push_back(-1);
            res.push_back(-1);
            return res;
        }
        else if(flag==1)
        {
            int temp=mid,temp1=mid;
            //cout<<"mid:"<<mid<<endl;
            cout<<"n:"<<n<<endl;
            while(temp>0&&nums[temp]==nums[temp-1])
            {
                temp--;
            }
            while(temp1<n-1&&nums[temp1]==nums[temp1+1])
            {
                temp1++;
            }
            res.push_back(temp);
            res.push_back(temp1);
        }
        return res;
    }
};
int main()
{
    int target=4;
    vector<int> a,res;
    a.push_back(1);
    a.push_back(4);
 //   a.push_back(2);
//    a.push_back(8);
//    a.push_back(8);
//    a.push_back(10);
    Solution s;
    res=s.searchRange(a,target);
    for(auto t:res)
    {
        cout<<t<<endl;
    }
    return 0;
}