题解 | #字符串合并处理#

#include <algorithm>
#include <cmath>
#include <iostream>
#include <vector>
using namespace std;

vector<int> getbits(int& n) {
    vector<int> bits;
    while (n != 0) {
        bits.push_back(n % 2);
        n /= 2;
    }
    while (bits.size() != 4)
        bits.push_back(0);
    return bits;
}

char bits_charac(vector<int>& bits) {
    int num = 0;
    for (int i = 0; i < 4; i++) {
        num += pow(2, 4 - i - 1) * bits[i];
    }
    if (0 <= num && num <= 9)
        return char(num + '0');
    else
        return char(num + 55);
}

void convert(char& c) {
    int value = -1;
    vector<int> bits;
    if ('0' <= c && c <= '9')
        value = c - '0';
    else if ('A' <= c && c <= 'F')
        value = c - 55;
    else if ('a' <= c && c <= 'f')
        value = c - 87;
    if(value!=-1){
        bits = getbits(value);
        c = bits_charac(bits);
    }
}

int main() {
    int  i, j;
    string str, str1, str2;
    cin >> str1 >> str2;
    str = str1 + str2;
    str1.clear();
    str2.clear();
    for (i = 0; i < str.size(); i++) {
        if (i % 2 == 0)  str1 += str[i];
        else    str2 += str[i];
    }
    str.clear();
    sort(str1.begin(), str1.end());
    sort(str2.begin(), str2.end());
    for (i = 0, j = 0; i < str1.size() && j < str2.size(); i++, j++) {
        str += str1[i];
        str += str2[j];
    }
    while (i != str1.size())
        str += str1[i++];
    while (j != str2.size())
        str += str2[j++];
    for (i=0; i<str.size(); i++) convert(str[i]);
    cout << str << endl;
}