/*
37.（字符串）
有 n 个长为 m+1 的字符串，
如果某个字符串的最后 m 个字符与某个字符串的前 m 个字符匹配，则两个字符串可以联接，
问这 n 个字符串最多可以连成一个多长的字符串，如果出现循环，则返回错误。
start time = 18:27
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*/#include <iostream>
#include <vector>
#include <string>
using namespace std;//判断两个字符串能否拼接 0表示不能 2表示s1在前 1表示s2在前
int contact(string s1, string s2, int m)
{if(s1.substr(0, m) == s2.substr(s2.length() - m, m))return 1;else if(s2.substr(0, m) == s1.substr(s1.length() - m, m))return 2;elsereturn 0;
}void getMax0(vector<int> now, vector<vector<int>> can_compare, vector<int> &max)
{ bool isfind = false;int last = now.back();vector<int>::iterator it;for(it = can_compare.at(last).begin(); it < can_compare.at(last).end(); it++){bool isHave = false;vector<int>::iterator it2;for(it2 = now.begin(); it2 < now.end(); it2++){if((*it) == (*it2)){isHave = true;break;}}if(isHave == false){isfind = true;now.push_back(*it);getMax0(now, can_compare, max);now.pop_back();}}if(isfind == false){if(now.size() > max.size()){max = now;}}
}
vector<int> getMax(vector<vector<int>> can_compare)
{vector<int> contact;vector<int> max;vector<int> now;vector<vector<int>>::iterator it;for(int i = 0; i < can_compare.size(); i++){now.push_back(i);getMax0(now, can_compare, max);now.clear();}return max;
}//返回可能的最大长度
string maxLength(vector<string> S, int m)
{//找到每个字符串在前时有哪些其他字符串可以与其匹配vector<vector<int>> can_compare;vector<string>::iterator it;for(it = S.begin(); it < S.end(); it++){vector<int> can_member;vector<string>::iterator it2;int n = 0;for(it2 = S.begin(); it2 < S.end(); it2++){if(it != it2){if(contact(*it, *it2, m) == 2){can_member.push_back(n);}}n++;}can_compare.push_back(can_member);}vector<int> maxStringMember = getMax(can_compare);vector<int>::iterator it3;string ans = S.at(maxStringMember.at(0));for(it3 = maxStringMember.begin() + 1; it3 < maxStringMember.end(); it3++){string after = S.at(*it3);ans.append(after.substr(after.length() - 1, 1));}cout << "the max length is "<< ans.length() << endl;cout << "the string is " << ans << endl;return ans;
}int main()
{vector<string> S;string s1 = "abd";S.push_back(s1);string s2 = "bcd";S.push_back(s2);string s3 = "cde";S.push_back(s3);string s4 = "def";S.push_back(s4);string ans = maxLength(S, 2);return 0;
}

#include <iostream>
#include <string>
using namespace std;#define INFINITY -10000
#define MAX_VERTEX_NUM 20 typedef struct MGraph{string vexs[MAX_VERTEX_NUM];//顶点信息，这里就是要处理的字符串，每个字符串看做一个顶点int arcs[MAX_VERTEX_NUM][MAX_VERTEX_NUM];//邻接矩阵，符合条件的两个字符串之间有边int vexnum, arcnum;//顶点数就是字符串的个数
}MGraph;void CreateDG(MGraph &G)//构造有向图
{int i, j;int m;cout<<"请输入要处理的字符串个数：";cin>>G.vexnum;cout<<"请输入这"<<G.vexnum<<"个字符串：";for(i=0; i<G.vexnum; i++)cin>>G.vexs[i];cout<<"请输入m：";cin>>m;for(i=0; i<G.vexnum; i++)for(j=0; j<G.vexnum; j++){if(G.vexs[i].substr(G.vexs[i].size()-m,m)==G.vexs[j].substr(0,m))//根据前后m个字符是否匹配确定两字符串之间是否有边G.arcs[i][j]=1;elseG.arcs[i][j]=INFINITY;}
}//利用弗洛伊德算法求各顶点间的最长路径，p保存路径，D保存各顶点间的最长路径，如果出现循环，函数返回false，反之返回true
bool Largeset_FLOYD(MGraph G, int p[MAX_VERTEX_NUM][MAX_VERTEX_NUM][MAX_VERTEX_NUM], int D[MAX_VERTEX_NUM][MAX_VERTEX_NUM])
{int v, w, u;int i, j;for(v=0; v<G.vexnum; v++)for(w=0; w<G.vexnum; w++){D[v][w]=G.arcs[v][w];for(u=0; u<G.vexnum; u++)p[v][w][u]=-1;if(D[v][w]>INFINITY){p[v][w][0]=v;p[v][w][1]=w;}}for(u=0; u<G.vexnum; u++)for(v=0; v<G.vexnum; v++)for(w=0; w<G.vexnum; w++){if(D[v][u]>INFINITY && D[u][w]>INFINITY && D[v][u]+D[u][w]>D[v][w] )//改进的弗洛伊德算法，求最长路径
                {D[v][w]=D[v][u]+D[u][w];//更新p，以便打印路径for(i=0; i<G.vexnum; i++){if(p[v][u][i]!=-1)p[v][w][i]=p[v][u][i];elsebreak;}for(j=1; j<G.vexnum; j++){if(p[u][w][j]!=-1)p[v][w][i++]=p[u][w][j];elsebreak;}}}//判断是否有循环for(v=0; v<G.vexnum; v++)if(D[v][v]!=INFINITY)return false;return true;
}void main()
{int i, j;int posx, posy;MGraph g;CreateDG(g);int p[MAX_VERTEX_NUM][MAX_VERTEX_NUM][MAX_VERTEX_NUM];int D[MAX_VERTEX_NUM][MAX_VERTEX_NUM];bool flag=true;flag=Largeset_FLOYD(g, p, D);/*    for(i=0; i<g.vexnum; i++){for(j=0; j<g.vexnum; j++)cout<<D[i][j]<<" ";cout<<endl;}*/if(flag){cout<<"最大长度为：";int max=-10000;for(i=0; i<g.vexnum; i++)for(j=0; j<g.vexnum; j++){if(D[i][j]>max){max=D[i][j];posx=i;posy=j;}}cout<<max<<endl;cout<<"字符串链为：";for(i=0; i<g.vexnum; i++)//打印字符串链
        {if(p[posx][posy][i]!=-1)cout<<g.vexs[p[posx][posy][i]]<<" ";}cout<<endl;}elsecout<<"错误：出现循环"<<endl;system("pause");}