Algorithm

=========

//使用关联数组map实现StringReorder

#include <cstdio>

#include <iostream>

#include <map>

#include <string>

using namespace std;

map<char,size_t> m;//使用关联数组保存字符和字符出现次数

string s;

int main(void)

{

return 0;

while(getline(cin,s))

{

int size = s.size();

bool is_true = true;

for(int i = 0; i < size; ++i)

{

if((s[i] >= '0' && s[i] <= '9') || (s[i] >= 'a' && s[i] <= 'z'))

{

++m[s[i]];//关联数组查找关键字，关键字不存在则建立关键字并初始化元素值为0，存在则自增

}

else

{

is_true = false;

}

}

if(is_true)

{

bool has_char = true;

while(has_char){

has_char = false;

for(map<char, size_t>::iterator iter = m.begin(); iter != m.end(); ++iter)

{

if(iter->second > 0){

printf("%c",iter->first);

--(iter->second);

has_char = true;

}

}

}

}

else

printf("<invalid input string>");

printf("\n");

}

return 0;

}