去哪儿网2015校招研发类笔试题

从网上找到的题目，自己做了一遍

1、二分查找

2、给定一个字符串，得到这个字符串中首先出现两次的那个字符

方法：可以用一个hash_map或者数组来存储字符出现的次数，一旦有一个出现了2次，就返回该字符

3、尝试在以下文本中搜索并打印出包含单词"your"(不区分大小写)的句子，并按照出现次数从高到低排序 

Make yourself at home
None of your business
I will be more careful
 How about going to a move?
Your life is your own affair

方法：统计每行中your出现的次数，然后 进行排序

代码：

#include<iostream>
#include<hash_map>
#include<vector>
#include<string>
#include<sstream>
#include<algorithm>
using std::vector;
using std::string;
using std::cout;
using std::cin;
using std::endl;
using std::hash_map;
using std::istringstream;
//题目1：二分查找
int bin_search(int num[], int start, int end, int n);
int bin_search(int num[],int length,int n)
{
    if (num==0||length<=0)
    {
        return false;
    }

    return bin_search(num, 0, length - 1, n);
}

int bin_search(int num[],int start,int end,int n)
{
    if (num==NULL||start<0||end<start||end<0)
    {
        throw std::exception("Invalid input");
    }

    if (start==end)
    {
        if (num[start] == n)
        {
            return start;
        }
        else
            return -1;
    }

    int mid = start + (end - start) / 2;
    if (num[mid]==n)
    {
        return mid;
    }
    else if (num[mid]<n)
    {
        return bin_search(num, mid + 1, end, n);
    }
    else
    {
        return bin_search(num, start, mid - 1, n);
    }
}

//题目2：字符串中第一次出现2次的字符

char occur2times(char* ch)
{
    char word = '';
    if (ch==NULL)
    {
        return word;
    }

    std::size_t length = strlen(ch);
    std::hash_map<char, int> hashmap;
    for (int i = 0; i < length;++i)
    {
        std::hash_map<char, int>::const_iterator itr= hashmap.find(ch[i]);
        if (itr==hashmap.cend())
        {
            hashmap.insert(std::make_pair(ch[i], 1));
        }
        else
        {
            word = itr->first;
            break;
        }
    }

    return word;
}

/*题目3：
尝试在以下文本中搜索并打印出包含单词"your"(不区分大小写)的句子，并按照出现次数从高到低排序
Make yourself at home
None of your business
I will be more careful
How about going to a move?
Your life is your own affair
*/
bool cmpValue(const std::pair<int, int>& lhs, const std::pair<int, int>& rhs)
{
    return lhs.second > rhs.second;  
}

void SentenceYour(const std::vector<string>& inputstr, std::vector<int>& output)
{
    if (inputstr.empty())
    {
        return;
    }


    //int *count = new int[inputstr.size()];
    //memset(count, 0, sizeof(int)*inputstr.size());
    
    hash_map<int, int> count;
    for (vector<string>::size_type line_num = 0; line_num != inputstr.size(); ++line_num)
    {
        istringstream line(inputstr[line_num]);
        string word;
        while (line>>word)
        {
            std::transform(word.begin(), word.end(), word.begin(), ::tolower);
            if (word=="your")
            {
                ++count[line_num];
            }
        }
    }

    vector<std::pair<int, int>> counts(count.begin(),count.end());

    std::sort(counts.begin(), counts.end(), cmpValue);
    for (vector<std::pair<int, int>>::const_iterator citr = counts.cbegin(); citr != counts.cend();++citr)
    {
        if (citr->second!=0)
        {
            output.push_back(citr->first);
        }
    }
}
int main()
{
    
    //题目1：
    int num[] = { 1, 2, 3, 4, 5, 6, 7, 8 };
    int n = 0;
    int pos = bin_search(num, 8, n);
    if (pos!=-1)
    {
        std::cout << n << "has found at " <<pos<< std::endl;
    }
    else
    {
        std::cout << n << "has not found" << std::endl;
    }

    //题目2
    char ch[] = "abcdedab";
    char a = occur2times(ch);
    if (a!='')
    {
        std::cout << "first char occured 2 times is " << a << std::endl;
    }
    else
    {
        std::cout << "no char occured 2 times  " << std::endl;

    }
    

    //题目3：
    vector<string> input;
    cout << "输入文本
";
    string line;
    while(getline(cin,line))
    {
        input.push_back(line);
    }
    vector<int> output;
    SentenceYour(input, output);
    if (!output.empty())
    {
        cout << "sentence have your are:
";
        vector<int>::const_iterator itr = output.begin();
        while (itr!=output.end())
        {
            cout << input[*itr++] << endl;
        }
    }
    else
    {
        cout << "no sentence have your
";

    }
    return 0;
}

输出：