微软2014年在线笔试题前两题

Description
　　For this question, your program is required to process an input string containing only ASCII characters between ‘0’ and ‘9’, or between ‘a’ and ‘z’ (including ‘0’, ‘9’, ‘a’, ‘z’).
　　Your program should reorder and split all input string characters into multiple segments, and output all segments as one concatenated string. The following requirements should also be met,
　　1. Characters in each segment should be in strictly increasing order. For ordering, ‘9’ is larger than ‘0’, ‘a’ is larger than ‘9’, and ‘z’ is larger than ‘a’ (basically following ASCII character order).
　　2. Characters in the second segment must be the same as or a subset of the first segment; and every following segment must be the same as or a subset of its previous segment.
　　Your program should output string “” when the input contains any invalid characters (i.e., outside the ’0′-’9′ and ‘a’-’z’ range).
　　Input
　　Input consists of multiple cases, one case per line. Each case is one string consisting of ASCII characters.
　　Output
　　For each case, print exactly one line with the reordered string based on the criteria above.
　　样例输入
　　aabbccdd
　　007799aabbccddeeff113355zz
　　1234.89898
　　abcdefabcdefabcdefaaaaaaaaaaaaaabbbbbbbddddddee
　　样例输出
　　abcdabcd
　　013579abcdefz013579abcdefz
　　
　　abcdefabcdefabcdefabdeabdeabdabdabdabdabaaaaaaa
我只实现了要求一，后面的还要再想想

#include <iostream>
#include <string>
using namespace std;

extern int max1=0;

void f(string s,int hash[]){
    int i,t;
    //将输入的字符存到hash数组其ASCII码对应的下标下，同时标记重复字符的最大值
    for(i= 0;i<s.size();i++)
    {
        t=int(s[i]);
        hash[t]++;
        if(hash[t]>max1)
            max1=hash[t];
    }

}

int _tmain(int argc, _TCHAR* argv[])
{
    string s;

    cout<<"Input:"<<endl;
    char c;

    getline(cin,s);
    int hash[200]={};
    f(s,hash);

    //遍历hash数组
    while(max1)
    {
        int i=0;
        for(i;i<200;i++)
        {
            if(hash[i]!=0)
            {
                if(hash[i]==max1)
                {
                    max1--;
                }
            c=(char)i;
            cout<<c;
            hash[i]--;
            }

      }
    }

    getchar();
    getchar();

    return 0;
}