题目描述

输入一个字符串,按字典序打印出该字符串中字符的所有排列。例如输入字符串abc,则打印出由字符a,b,c所能排列出来的所有字符串abc,acb,bac,bca,cab和cba。

代码实现

class Solution {

public:
    vector<string> permutation;
    set<string> permutationSet;

    vector<string> Permutation(string str) {
        if (str.size() != 0)
        {
            int nSize = str.size();
            Permutation(str, nSize, 0);
        }
        for (set<string>::iterator iter = permutationSet.begin(); iter != permutationSet.end(); ++iter)
        {
            permutation.push_back(*iter);
        }
        return permutation;
    }

    void Permutation(string str,int nSize, int n)
    {
        if (n == str.size())
        {
            permutationSet.insert(str);
        }

        else
        {
            Permutation(str, nSize, n + 1);
            for (int i = n+1; i < str.size(); ++i)
            {
                if (str[n] != str[i])
                {
                    char tmp = str[n];
                    str[n] = str[i];
                    str[i] = tmp;

                    Permutation(str, nSize, n + 1);

                    tmp = str[n];
                    str[n] = str[i];
                    str[i] = tmp;
                }
            }
        }
    }
};