华为笔试题总结

一、查找连续出现次数最多的字符（可以用哈希，但不用哈希会更方便）

#include<stdio.h>
int main(void)
{
    char a[128] = { 0 };
    int char_count = 0;
    int char_max = 0;
    char find_char;
    scanf_s("%s",a,128);
    int length = strlen(a);
    int i = 0;
    char_count = 1;
    for (i = 1; i < length; i++)
    {
        if (a[i] == a[i -1])
        {
            char_count = char_count + 1;
            continue;
        }
    
        if (char_max == char_count && find_char > a[i - 1])
        {
                find_char = a[i - 1];
        }
        else if (char_max < char_count)
        {
            char_max = char_count;
            find_char = a[i - 1];
        }
        char_count = 1;
    }
    if (char_max == char_count && find_char > a[i - 1])
    {
        find_char = a[i - 1];
    }
    else if (char_max < char_count)
    {
        char_max = char_count;
        find_char = a[i - 1];
    }
    for (i = 0; i < char_max; i++)
        printf("%c", find_char);
    while (1);
    return 0;
}

 用哈希的方法：

/*****
问题：统计出一个字符串中连续出现字母最多的字符串
比如：
aaaaaaaaabbbbbbbbccccccccccccddddddddaaaaaa
会输出ccccccccccccc（如果相等按照ascii码顺序)
*****/
#include<stdio.h>
#include<string.h>
int main()
{
    char s[128] = { 0 };
    int count[26] = { 0 };
    int count_temp[26] = { 0 };
    int len = 0, i = 0;
    int max_num, max_index;
    int temp = 0;
    scanf_s("%s", s,128);
    len = strlen(s);
    count_temp[s[0] - 'a'] = 1;
    //连续字符查找，使用hash的方法
    for (i = 1; i < len; i++)
    {
        if (s[i] == s[i - 1])
        {
            count_temp[s[i] - 'a']++;
            continue;
        }
        if (count[s[i -1 ] - 'a'] < count_temp[s[i -1] - 'a'])
        {
            count[s[i-1] - 'a'] = count_temp[s[i-1] - 'a'];
        }
        count_temp[s[i - 1] - 'a'] = 0;
        count_temp[s[i] - 'a'] = 1;
    }
    //最后一个字符的次数，上述没有去对比，所以又对比了一次。
    if (count[s[i - 1] - 'a'] < count_temp[s[i - 1] - 'a'])
    {
        count[s[i - 1] - 'a'] = count_temp[s[i - 1] - 'a'];
    }
    max_num = count[0];
    max_index = 0;
    for (i = 1; i < 26; i++)
    {
        if (count[i] > max_num)
        {
            max_num = count[i];
            max_index = i;
        }
    }
    for (i = 0; i < max_num; i++)
    {
        printf("%c", max_index + 'a');
    }
    while (1);
    return 0;
}

二、查找一个次数出现最多的字符（用哈希）

/*也可以演变为:来统计每个字符出现的次数和出现的字符个数（value值一直重复赋值为1）

#include <iostream>
#include <string>
using namespace std;
int main()
{
　　string s;
　　getline(cin ,s);
　　int ar[128] = {0};
　　for (int i = 0; i < s.length(); ++i) {
　　 　　ar[int(s[i])]++;
　　}
　　int num = 0;
　　for (int j = 0; j < 128; ++j) {
　　if(ar[j])
　　　　 num++;
　　}
　　cout << num << endl;
　　return 0;
}

三、统计字符串中某个字符串的个数，不区分大小写。

#include<stdio.h>
#include<string.h>
int main(int argc, char **argv)
{
    char a[1000] = { 0 };
    char b = 0;
    gets(a);
    b = getchar();
    int count_number = 0;
    switch (b)
    {
    　　case '0'...'9':
    　　{
            for (int i = strlen(a) - 1; i >= 0; i--)
            {
                 if (b == a[i])
                      count_number++;
            }
    　　}
        break;
    　　case  'a' ... 'z':
    　　{
            for (int i = strlen(a) - 1; i >= 0; i--)
            {
                 if (b == a[i] || b - 32 == a[i])
                         count_number++;
            }
    　　}
        break;
    　　case  'A' ... 'Z':
    　　{
             for (int i = strlen(a) - 1; i >= 0; i--)
             {
                  if (b == a[i] || b + 32 == a[i])
                         count_number++;
             }
    　　}
        break;
    }
    printf("%d\n", count_number);
    return 0;
}

四、长整数相加

#include<stdio.h>
#include<string.h>
#include<stdlib.h>

#define min(a,b) ((a>b)?b:a)
#define max(a,b) ((a>b)?a:b)

void add(char array_a[], char array_b[])
{
    int length_a = strlen(array_a);
    int length_b = strlen(array_b);
    printf("%d,%d\n", length_a, length_b);
    int min_length = min(length_a, length_b);
    char i = 0;
    char flag = 0;
    char sum = 0;
    for (i = 0; i < min_length; i++)
    {
        (sum = ((array_a[i] - '0') + (array_b[i] - '0') + flag)) >= 10 ? (flag = 1, array_a[i] = sum - 10 + '0') : (flag = 0, array_a[i] = sum + '0');
    }
    if (length_a > min_length)
    {
        for (i = min_length; i < length_a; i++)
        {
            (sum = ((array_a[i] - '0') + flag)) >= 10 ? (flag = 1, array_a[i] = sum - 10 + '0') : (flag = 0, array_a[i] = sum + '0');
        }
    }
    if (length_b > min_length)
    {
        for (i = min_length; i < length_b; i++)
        {
            (sum = ((array_b[i] - '0') + flag)) >= 10 ? (flag = 1, array_a[i] = sum - 10 + '0') : (flag = 0, array_a[i] = sum + '0');
        }
    }
    if (1 == flag)
    {
        array_a[i] = flag + '0';
    }
}

//反转字符串或者数组
void mystrrev(char *a)
{
    int len = strlen(a);
    char temp = 0;
    char i;
    for (i = 0; i < len / 2; i++)
    {
        temp = a[i];
        a[i] = a[len - i - 1];
        a[len - i - 1] = temp;
    }
}
int main(int argc, char **argv)
{
    char *a = malloc(100);
    memset(a, 100, '\0');
    if (NULL == a){
        printf("malloc is error\n");
    }
    char *b = malloc(100);
    if (NULL == b){
        printf("malloc is error\n");
    }
    memset(b, 100, '\0');
    scanf_s("%s", a, 100);
    scanf_s("%s", b, 100);
    mystrrev(a);
    mystrrev(b);
    add(a, b);
    mystrrev(a);
    printf("%s", a);
    system("pause");
    return 0;
}

五、找字符串

#include<stdio.h>
#include<string.h>
#define min(a,b) ((a > b)?(b):(a))
int main(int argc, char **argv)
{
    char str[1000];
    gets_s(str,1000);
    int len = strlen(str);
    int count_num = 0;
    int max = 0;
    int local_pos = 0;//记录下位置
    char douhao_flag = 0;
    int i = 0;
    for (i = 0; i < len; i++)
    {
        if (str[i] >= '0' && str[i] <= '9' || str[i] == '.' || str[i] == '+' || str[i] == '-')
        {
            if (str[i] == '+' || str[i] == '-')
            {
                count_num = 0;//如果有正负号开始重新计数，确保每次只有一个正负号
            }
            if (str[i] == '.')
            {
                if (douhao_flag == 1)//确保逗号不能有两个
                {
                    count_num = 0;
                    douhao_flag = 0;
                }
                if (count_num == 0)//确保前面有数字，下面确保前面数字不为+-号
                {
                    continue;
                }
                else
                {
                    if (count_num == 1 && str[i - 1] == '+' && str[i - 1] == '-')//确保+-号后不为逗号
                    {
                        count_num = 0;
                        continue;
                    }
                    else
                    {
                        if (str[i + 1] >= '0' && str[i + 1] <= '9')//确保.号后为数字
                            douhao_flag = 1;
                        else
                            continue;
                    }
                }
            }
            count_num++;
            if (count_num >= max)
            {
                max = count_num;
                local_pos = i - max + 1;
            }
        }
        else
        {
            count_num = 0;//不是数字清0
            douhao_flag = 0;
        }
    }
    //输出字符串
    for (i = 0; i < max; i++)
    {
        if (max == 1 && (str[i + local_pos] == '+' || str[i + local_pos] == '-' || str[i + local_pos] == '.'))
            printf("");
        else
            printf("%c", str[i + local_pos]);
    }
    if (0 == max)//返回空字符串
    {
        printf("");
    }
    printf("\n");
    while (1);
    return 0;
}