hdu 1811 Rank of Tetris （拓扑排序+并查集）

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <queue>
#define MAXN 20005
using namespace std;

struct ArcNode
{
    int to;
    struct ArcNode * next;
};

struct ArcNode * List[MAXN];
int Indegree[MAXN], father[MAXN];
char str[MAXN];
int start[MAXN], finish[MAXN];
int mark1, mark2, num;

void Init(int n)    //初始化操作
{
    mark1 = 0;      mark2 = 0;
    num = n;
    for(int i = 0; i<n; i++)
    {
        father[i] = i;
        Indegree[i] = 0;
        List[i] = NULL;
    }
}

int FindSet(int x)     //查找父节点
{
    if(x != father[x])
    {
        father[x] = FindSet(father[x]);
    }

    return father[x];
}

void Topological(int n)    //拓扑排序，用队列来模拟
{
    int j, k;
    queue <int> Q;
    struct ArcNode * temp;


    for(int i = 0; i<n; i++)
    {
        if(Indegree[i] == 0 && i == FindSet(i))
        {
            Q.push(i);
        }
    }
    while(!Q.empty())
    {
        if(Q.size() > 1)     //每次只有一个度为0的节点才不会有不确定的关系
            mark1 = 1;
        j = Q.front();
        Q.pop();    num--;  //num用来判断是否是否有环
        temp = List[j];
        while(temp != NULL)
        {
             k = temp->to;
             if(--Indegree[k] == 0)
             {
                 Q.push(k);
             }
             temp = temp->next;
        }
    }
    if(num >1)
        mark2 = 1;
}

int main()
{
    int x, y;
    int n, m, u, v;
    struct ArcNode * temp;
    while(scanf("%d%d", &n, &m)!=EOF)
    {
        Init(n);
        for(int i = 0; i<m; i++)
        {
            scanf("%d %c %d", &start[i], str+i, &finish[i]);
            if(str[i] == ‘=‘)
            {
                num--;     //求出真正有几个独立的集合
                x = FindSet(start[i]);
                y = FindSet(finish[i]);
                if(x != y)
                    father[y] = x;
            }
        }
        for(int i = 0; i<m; i++)
        {
            if(str[i] == ‘=‘)
                continue;
            if(str[i] == ‘>‘)
            {
                u = FindSet(start[i]);
                v = FindSet(finish[i]);
            }
            if(str[i] == ‘<‘)
            {
                u = FindSet(finish[i]);
                v = FindSet(start[i]);
            }
             Indegree[v]++;
             if(u == v)      //同一个集合是没有大小却按照RP来排序，这里却有大小，明显有矛盾
                mark2 = 1;
            temp = (struct ArcNode *)malloc(sizeof(struct ArcNode));
            temp->to = v;       temp->next = NULL;
            if(List[u] == NULL)
                List[u] = temp;
            else
            {
                temp->next = List[u];
                List[u] = temp;
            }
        }

        Topological(n);

        if(mark2)
            printf("CONFLICT\n");
        else if(!mark2 && mark1)
            printf("UNCERTAIN\n");
        else
            printf("OK\n");

    }

    return 0;
}