字符串中最大子串问题

输入一个字符串，输出其最大子串长度，即子串中任两个字符不相同 。本程序只能输入字母，空格以及逗号，并且不区分大小写，输出为第一个具有最大长度的子串以及其长度。

 

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

int chartoi(char c)
...{
    if(isalnum(c))
        ...{
            if(isalpha(c))
                return tolower(c)-'a';
            else
                return c-'0'+26;
    }
    else
        if(isspace(c))
            return 36;
        else if(c==',')
            return 37;
        else
        ...{
            cout<<"error input char"<<endl;
            exit(0);
        }
}

int substr(char* str, int len)
...{
    int A[38]=...{0};
    int i,j;
    int maxlen=0,templen;
    int beg=0,end=0;
    for(i=0,j=0;i<len,j<len; ++j)
    ...{
        int num=chartoi(str[j]);
        if(A[num]==0)
            A[num]=1;
        else
        ...{
            A[num]+=1;
            int step;
            for(step=i;step<=j;++step)//
            ...{
                int num1=chartoi(str[step]);
                if(A[num1]>1)
                ...{
                    --A[num1];
                    break;
                }
            }
        
            i=step+1;

        }
        templen=j-i+1;
        if(templen>maxlen)
        ...{
            beg=i;
            end=j;
            maxlen=templen;
        }
    }
    for(i=beg;i<=end;++i)
        cout<<str[i];
    cout<<endl;

    return maxlen;
}

int main()
...{
    char str[]="good morning, everyone";
    cout<<str<<endl;
    cout<<substr(str,strlen(str))<<endl;
    return 0;
}