poj 1094 拓扑排序

这题就是朴素的拓扑排序，只是一开始题意没看清楚，不太清楚几种结果的优先级。

优先级其实就是给的测试数据的结果。

#include<iostream>
#include<cstdio>
#include<cstring>
#include<algorithm>
#include<queue>
#define Maxn 102
#define Maxm 10010
using namespace std;
int graphic[Maxn][Maxn],indegree[Maxn],n,m,e;
char ans[Maxn];
int Topsort()
{
    int i,j,k,num,temp,f=0;
    temp=0;
    for(i=1;i<=n;i++)
    {
        num=0;
        for(j=1;j<=n;j++)
        {
            if(indegree[j]==0)
                num++;
        }
        if(num>1)
            f=1;
        for(j=1;j<=n;j++)
        {
            if(indegree[j]==0)
            {
                indegree[j]--;
                ans[e++]=j+'A'-1;
                for(k=1;k<=n;k++)
                {
                    if(graphic[j][k])
                        indegree[k]--;
                }
                temp++;
                break;
            }
        }
    }
    //cout<<"*"<<temp<<endl;
    if(temp<n)
        return -1;
    if(f)
        return 0;
    return 1;
}
int main()
{
    int i,j,a,b;
    char str[Maxm][10];
    //freopen("ans.txt","w",stdout);
    while(scanf("%d%d",&n,&m)!=EOF,n||m)
    {
        memset(graphic,0,sizeof(graphic));
        memset(indegree,0,sizeof(indegree));
        e=0;
        int temp,pos;
        for(i=0;i<m;i++)
        {
            scanf("%s",&str[i]);
            memset(indegree,0,sizeof(indegree));
            memset(graphic,0,sizeof(graphic));
            for(j=0;j<=i;j++)
            {
                if(!graphic[str[j][0]-'A'+1][str[j][2]-'A'+1])
                {
                indegree[str[j][2]-'A'+1]++;
                graphic[str[j][0]-'A'+1][str[j][2]-'A'+1]=1;
                }
            }
            e=0;
            temp=Topsort();
            if(temp==1)
            {  //cout<<e<<endl;
                pos=i+1;
                ans[e]='\0';
                break;
            }
            if(temp==-1)
            {
                pos=i+1;
                break;
            }
        }
        //cout<<i<<"&&"<<endl;
        for(i++;i<m;i++)
        {
            scanf("%s",&str[i]);
            //cout<<i<<endl;
        }//cout<<temp<<" **"<<endl;
        if(temp==-1)
        {
            printf("Inconsistency found after %d relations.\n",pos);
        }
        if(temp==1)
        {
            printf("Sorted sequence determined after %d relations: %s.\n",pos,ans);
        }
        if(temp==0)
            printf("Sorted sequence cannot be determined.\n");
    }
    return 0;
}

 给个邻接表的拓扑，果断0ms：

#include<iostream>
#include<cstdio>
#include<cstring>
#include<algorithm>
#include<queue>
#define Maxn 102
#define Maxm 10010
using namespace std;
struct Edge{
    int to,next;
}edge[Maxm];
int graphic[Maxn][Maxn],indegree[Maxn],n,m,e,index[Maxn],r;
char ans[Maxn];
int Topsort()
{
    int i,j,k,num,temp,f=0;
    temp=0;
    for(i=1;i<=n;i++)
    {
        num=0;
        for(j=1;j<=n;j++)
        {
            if(indegree[j]==0)
                num++;
        }
        if(num>1)
            f=1;
        for(j=1;j<=n;j++)
        {
            if(indegree[j]==0)
            {
                indegree[j]--;
                ans[e++]=j+'A'-1;
                for(k=index[j];k!=-1;k=edge[k].next)
                {
                    indegree[edge[k].to]--;
                }
                temp++;
                break;
            }
        }
    }
    //cout<<"*"<<temp<<endl;
    if(temp<n)
        return -1;
    if(f)
        return 0;
    return 1;
}
void addedge(int from ,int to)
{
    edge[r].to=to;
    edge[r].next=index[from];
    index[from]=r++;
}
int main()
{
    int i,j,a,b;
    char str[Maxm][10];
    //freopen("ans.txt","w",stdout);
    while(scanf("%d%d",&n,&m)!=EOF,n||m)
    {
        memset(graphic,0,sizeof(graphic));
        memset(indegree,0,sizeof(indegree));
        memset(index,-1,sizeof(index));
        e=0;
        int temp,pos;
        for(i=0;i<m;i++)
        {
            scanf("%s",&str[i]);
            memset(indegree,0,sizeof(indegree));
            memset(graphic,0,sizeof(graphic));
            memset(index,-1,sizeof(index));
            r=0;
            for(j=0;j<=i;j++)
            {
                if(!graphic[str[j][0]-'A'+1][str[j][2]-'A'+1])
                {
                addedge(str[j][0]-'A'+1,str[j][2]-'A'+1);
                indegree[str[j][2]-'A'+1]++;
                graphic[str[j][0]-'A'+1][str[j][2]-'A'+1]=1;
                }
            }
            e=0;
            temp=Topsort();
            if(temp==1)
            {  //cout<<e<<endl;
                pos=i+1;
                ans[e]='\0';
                break;
            }
            if(temp==-1)
            {
                pos=i+1;
                break;
            }
        }
        //cout<<i<<"&&"<<endl;
        for(i++;i<m;i++)
        {
            scanf("%s",&str[i]);
            //cout<<i<<endl;
        }//cout<<temp<<" **"<<endl;
        if(temp==-1)
        {
            printf("Inconsistency found after %d relations.\n",pos);
        }
        if(temp==1)
        {
            printf("Sorted sequence determined after %d relations: %s.\n",pos,ans);
        }
        if(temp==0)
            printf("Sorted sequence cannot be determined.\n");
    }
    return 0;
}