1049 数列的片段和 （20 分）

Posted 2021-02-11 chance-zou

需要注意的一点：

当B的长度小于A的长度时，需要的B的前面补零。

#include <iostream>
#include<string>
#include<algorithm>
using namespace std;
int main()
{
    string str1, str2;
    cin >> str1 >> str2;
    int len1 = str1.length();
    int len2 = str2.length();
    char str1_f[105], str2_f[105];
    int str3_f[105];
    //将两个字符串倒置
    //reverse(begin,end)会将区间[begin,end)内的元素全部逆序
    //reverse(str1.begin().str1.end());
    for (int i = 1;i <= len1;i++) {
        str1_f[i] = str1[len1 - i];
    }
    for (int i = 1;i <= len2;i++) {
        str2_f[i] = str2[len2 - i];
    }
    //B的长度小于等于A的长度时，
    if (len2 <= len1) {
        for (int i = 1;i <= len2;i++) {
            if (i % 2 == 0) {//偶数位时
                int b = str2_f[i] - str1_f[i];
                if (b < 0) {
                    b += 10;
                }
                str3_f[i] = b;
            }
            else {//奇数位时
                int b = str2_f[i] - '0' + str1_f[i] - '0';
                b = b % 13;
                str3_f[i] = b;
            }
        }
        //需要在B的前面补零
        for (int j = len2 + 1;j <= len1;j++) {
            if (j % 2 == 0) {//偶数位时
                int b = '0' - str1_f[j];
                if (b < 0) {
                    b += 10;
                }
                str3_f[j] = b;
            }
            else {//奇数位时
                int b = str1_f[j] - '0';
                str3_f[j] = b;
            }
        }
        for (int j = len1;j > 0;j--) {
            if (str3_f[j] < 10) {
                cout << str3_f[j];
            }
            else {
                if (str3_f[j] == 10) {
                    cout << 'J';
                }
                if (str3_f[j] == 11) {
                    cout << 'Q';
                }
                if (str3_f[j] == 12) {
                    cout << 'K';
                }
            }
        }

    }
    //B的长度大于A的长度时
    else {//len2大于len1时
        for (int i = 1;i <= len1;i++) {
            if (i % 2 == 0) {//偶数位时
                int b = str2_f[i] - str1_f[i];
                if (b < 0) {
                    b += 10;
                }
                str3_f[i] = b;
            }
            else {//奇数位时
                int b = str2_f[i] - '0' + str1_f[i] - '0';
                b = b % 13;
                str3_f[i] = b;
            }
        }
        for (int i = len1 + 1;i <= len2;i++) {
            str3_f[i] = str2_f[i]-'0';
        }
        for (int j = len2;j > 0;j--) {
            if (str3_f[j] < 10) {
                cout << str3_f[j];
            }
            else {
                if (str3_f[j] == 10) {
                    cout << 'J';
                }
                if (str3_f[j] == 11) {
                    cout << 'Q';
                }
                if (str3_f[j] == 12) {
                    cout << 'K';
                }
            }
        }
    }
    
    return 0;
}