华为oj 字符串合并处理

#include <iostream>
#include <string>
#include <cstring>
#include <algorithm>
#include <map>
using namespace std;
const int MAX_N=100000;
int change[] = { 0, 8, 4, 12, 2, 10, 6, 14, 1, 9, 5, 13, 3, 11, 7, 15 };
int main(){
map<char,char> m;
for(int i=0;i<16;i++)
if(i<10)    m[i+'0']=(change[i]>9?change[i]-10+'A':change[i]+'0');
else   m[i-10+'a']=(change[i]>9?change[i]-10+'A':change[i]+'0'),
m[i-10+'A']=(change[i]>9?change[i]-10+'A':change[i]+'0');
string str1, str2;
cin >> str1 >> str2;
string str = str1 + str2;
string::size_type i = 0, j = 0, k = 0, _size = str.size();
str1.resize((_size + 1) / 2);
str2.resize(_size / 2);
for (i = 0; i<_size; i++)
if (i & 1)  str2[k++] = str[i];
else    str1[j++] = str[i];
sort(str1.begin(), str1.end());
sort(str2.begin(), str2.end());
for (j = 0; j<(_size + 1) / 2; j++){
map<char,char>::iterator iter=m.find(str1[j]);
if(iter!=m.end())   str[2*j]=m[str1[j]];
else        str[2*j]=str1[j];
}
for (j = 0; j<_size / 2; j++){
map<char,char>::iterator iter=m.find(str2[j]);
if(iter!=m.end())   str[2*j+1]=m[str2[j]];
else    str[2*j+1]=str2[j];
}
cout << str << endl;
return 0;
}