牛客网——华为机试题库（1-10）

1、字符串最后一个单词的长度

#include 

using namespace std;

int main()
{
    string str;
    getline(cin, str);
    int len = 0;
    for(int i = str.size()-1; i >= 0 && str[i] != ' '; --i)
    {
        ++len;
    }
    cout << len << endl;
    
    return 0;
}

2、计算字符个数

#include 

using namespace std;

int main()
{
    string str;
    char s;
    getline(cin, str);
    cin >> s;
    int count = 0;
    for(int i = 0; i < str.size(); ++i)
    {
        if(str[i] == s || str[i] == s+32 || str[i] == s-32)
            count++;
    }
    cout << count << endl;
    
    return 0;
}

3、明明的随机数

#include 
#include 

using namespace std;

int main()
{
    int num;
    int n;
    while(cin >> num)
    {
        unordered_map<int, int> hash;
        while(num--)
        {
            cin >> n;
            hash[n] = 1;
        }
        for(int i = 0; i < hash.size(); i++)
        {
            if(hash[i] == 1)
            cout << i << endl;
        }
    }
    
    return 0;
}

4、字符串分隔

#include 

using namespace std;

int main()
{
    string str;
    while(getline(cin, str))
    {
        while(str.size() > 8)
        {
            cout << str.substr(0, 8) << endl;
            str = str.substr(8);
        }
        cout << str.append(8 - str.size(), '0') << endl;
    }
    
    return 0;
}

5、进制转换

#include 

using namespace std;

int main()
{
    string str;
    while(getline(cin, str))
    {
        if(str.size() < 0)
            break;
        //超出int范围
        int num = 0;
        for(int i = 2; i < str.size(); ++i)
        {
            if(str[i] >= '0' && str[i] <= '9')
            {
                num = num * 16 + str[i] - '0';
            }
            if(str[i] >= 'A' && str[i] <= 'F')
            {
                num = num *16 + str[i] - 'A' + 10;
            }
        }
        cout << num << endl;
    }
    
    return 0;
}

6、质数因子

#include 

using namespace std;

int main()
{
    long n;
    cin >> n;
    //for循环从小到大输出质因子
    for(int i = 2; i <= n; ++i)
    {
        while(n % i == 0)
        {
            cout << i << ' ';
            n /= i;
        }
    }
    cout << endl;
    
    return 0;
}

7、取近似值

#include 

using namespace std;

int main()
{
    //浮点数尽量用double
    double n;
    cin >> n;
    int a = (int)n;
    int b = (n - a) * 10;
    if(b >= 5)  
        cout << a+1 << endl;
    else 
        cout << a << endl;
    
    return 0;
}

8、合并表记录

#include 
#include 
#include 
#include 

using namespace std;

int main()
{
    int num;
    cin >> num;
    unordered_map<int, int> hash;
    vector<int> key;
    while(num--)
    {
        int index, value;
        cin >> index >> value;
        key.push_back(index);//有重复的
        hash[index] +=value;
    }
    //key去重
    sort(key.begin(), key.end());
    key.erase(unique(key.begin(), key.end()), key.end());
    for(auto x : key)
        cout << x << ' ' << hash[x] << endl;
    /*
    for(int i = 0; i < hash.size(); ++i)
    {
        if(hash[i] != 0)
            cout << i << ' ' << hash[i] <
    
    return 0;
}

9、提取不重复的整数

#include 
#include 

using namespace std;

int main()
{
    int num;
    int out;
    cin >> num;
    unordered_map<int, int> hash;
    while(num)
    {
        if(hash[num % 10] == 0)
        {
            hash[num %10] = 1;
            out = out * 10 + num % 10;
        }
        num /= 10;
    }
    cout << out << endl;
    
    return 0;
}

10、字符个数统计

#include 
#include 

using namespace std;

int main()
{
    int sum = 0;
    char c;
    unordered_map<char, int> hash;
    while(cin >> c)
    {
        hash[c] = 1;
    }
    for(int i = 0; i < hash.size(); ++i)
    {
        //ascii  0  ''
        if(hash[i] == 1)//if(hash[' ' + i] == 1)也是对的
            sum++;
    }
    cout << sum << endl;
    
    
    return 0;
}