1048 数字加密（附详细注释，逻辑分析）

写在前面

• 实现思路

• 字符数组封装字符串
• 数字反转后，遍历逐位累加转换；不足位数补0参与计算
• 结果反转，打印输出

• 题目较简单，15分钟a题

• 最近略疲劳（代码撸多伤身），时间维度把握可能偏差

测试用例

input:
1234567 368782971
output:
3695Q8118

ac代码

• 算法笔记（基础版）

#include <cstdio>
#include <cstring>

const int maxn = 110;
const char ch[13] = {}
char a[maxn],b[maxn],ans[maxn] = {0};
void reverse_udf(char s[])
{
    int len = strlen(s);
    for(int i=0; i<len/2; i++)
    {
        int tmp = s[i];
        s[i] = s[len-1-i];
        s[len-1-i] = tmp;;
    }
}

int main()
{
    scanf("%s %s", a, b);
    reverse_udf(a);
    reverse_udf(b);

    int lenA = strlen(a);
    int lenB = strlen(b);
    int len = lenA > lenB ? lenA : lenB;
    for(int i=0; i<len; i++)
    {
        int numA = i < lenA ? a[i]-'0' : 0;
        int numB = i < lenB ? b[i]-'0' : 0;
        if(i%2 == 0)
        {
            int tmp = (numA + numB)%13;
            if(tmp==10) ans[i] = 'J';
            else if(tmp==11) ans[i] = 'Q';
            else if(tmp==12) ans[i] = 'K';
            else ans[i] = tmp + '0';
        }
        else
        {
            int tmp = numB-numA;
            if(tmp<0) tmp+=10;
            ans[i] = tmp+'0';
        }
    }
    reverse_udf(ans);
    printf("%s", ans);
//    puts(ans);

    return 0;
}

• 优化后

#include <cstring>
#include <iostream>
#include <algorithm>
using namespace std;

const int maxn = 110;
const char ch[13] = {'0','1','2','3','4','5','6','7','8','9','J','Q','K'};
char a[maxn],b[maxn],ans[maxn] = {0};
int main()
{
    scanf("%s %s", a, b);

    int lenA = strlen(a);
    int lenB = strlen(b);
    reverse(a,a+lenA);
    reverse(b,b+lenB);

    int len = max(lenA, lenB);
    for(int i=0; i<len; i++)
    {
        int numA = i < lenA ? a[i]-'0' : 0;
        int numB = i < lenB ? b[i]-'0' : 0;
        if(i%2 == 0)
            ans[i] = ch[(numA + numB)%13];
        else
            ans[i] = (numB-numA+10)%10+'0';
    }
    reverse(ans, ans+strlen(ans));
    printf("%s", ans);

    return 0;
}

学习代码

• ​​1048. 数字加密(20).cpp​​

• 知识点

• 字符串补零实现
• 字符数组初始化实现，不同之处

char str[14] = {"0123456789JQK"};
const char ch[13] = {'0','1','2','3','4','5','6','7','8','9','J','Q','K'};

#include <iostream>
#include <algorithm>
using namespace std;
int main() {
    string a, b, c;
    cin >> a >> b;
    int lena = a.length(), lenb = b.length();
    reverse(a.begin(), a.end());
    reverse(b.begin(), b.end());
    if (lena > lenb) 
        b.append(lena - lenb, '0');
    else
        a.append(lenb - lena, '0');
    char str[14] = {"0123456789JQK"};
    for (int i = 0; i < a.length(); i++) {
        if (i % 2 == 0) {
            c += str[(a[i] - '0' + b[i] - '0') % 13];
        } else {
            int temp = b[i] - a[i];
            if (temp < 0) temp = temp + 10;
            c += str[temp];
        }
    }
    for (int i = c.length() - 1; i >= 0; i--)
        cout << c[i];
    return 0;
}