//poj1094 写了两个DFS,TLE 话说我输入一次它就来两个DFS,能不TLE吗?
//我看Discuss有测试数据,跑了一下,真的很慢,脑残的孩子果然只有慢慢学。
//贴一份TLE的代码,备份一下,说不定哪天我可以继续优化,然后AC。
#include <iostream>
#include <algorithm>
#include <string>
using namespace std;
int top = 0;
bool isSource[31];
bool isCircle;
bool isComplete;
int list[31][31];
int child[31];
bool mark[31];
int stack[1000000];
bool tempMark[31];
bool allMark(int n)
{
for (int i = 0; i < n; i++)
{
if (!mark[i])
return false;
}
return true;
}
bool dfs()
{
for (int i = 0; i < child[stack[top - 1]]; i++)
{
if (mark[list[stack[top - 1]][i]])
return true;
else
{
mark[list[stack[top - 1]][i]] = true;
tempMark[list[stack[top - 1]][i]];
stack[top++] = list[stack[top - 1]][i];
if (dfs())
return true;
}
}
mark[stack[top - 1]] = false;
top--;
if (top == 0)
return false;
return false;
}
bool dfs2(int n)
{
if (allMark(n))
return true;
for (int i = 0; i < child[stack[top - 1]]; i++)
{
if (!mark[list[stack[top - 1]][i]])
{
mark[list[stack[top - 1]][i]] = true;
tempMark[list[stack[top - 1]][i]] = true;
stack[top++] = list[stack[top - 1]][i];
if (dfs2(n))
return true;
}
}
mark[stack[top - 1]] = false;
top--;
if (top == 0)
return false;
return false;
}
void checkIsCircle(int n)
{
memset(tempMark, 0, sizeof(tempMark));
for (int i = 0; i < n; i++)
{
if (tempMark[i])
continue;
top = 0;
memset(mark, 0, sizeof(mark));
stack[top++] = i;
mark[i] = true;
tempMark[i] = true;
if (dfs())
{
isCircle = true;
return;
}
}
}
void checkIsComplete(int n)
{
memset(tempMark, 0, sizeof(tempMark));
for (int i = 0; i < n; i++)
{
if (isSource[i] && !tempMark[i])
{
top = 0;
memset(mark, 0, sizeof(mark));
stack[top++] = i;
mark[i] = true;
tempMark[i] = true;
if (dfs2(n))
{
isComplete = true;
return;
}
}
}
}
int main()
{
int n, m;
cin >> n >> m;
while (n && m)
{
isCircle = false;
isComplete = false;
bool ok = false;
for (int i = 0; i < n; i++)
{
isSource[i] = true;
mark[i] = false;
child[i] = 0;
for (int j = 0; j < n; j++)
list[i][j] = 0;
}
for (int i = 0; i < m; i++)
{
char s, c, t;
cin >> s >> c >> t;
int st = s - 'A';
int ed = t - 'A';
if (c == '<')
{
list[st][child[st]++] = ed;
isSource[ed] = false;
}
else
{
list[ed][child[ed]++] = st;
isSource[st] = false;
}
//对于是有向图的起点的,采用遍历看是否有环,然后看是否完整。
checkIsCircle(n);
if (isCircle && !ok)
{
cout << "Inconsistency found after " << i + 1 << " relations." << endl;
ok = true;
}
else
{
checkIsComplete(n);
if (isComplete && !ok)
{
cout << "Sorted sequence determined after " << i + 1 << " relations: ";
for (int i = 0; i < top; i++)
cout << char('A' + stack[i]);
cout << "." << endl;
ok = true;
}
}
}
if (!isCircle && !isComplete)
cout << "Sorted sequence cannot be determined." << endl;
cin >> n >> m;
}
return 0;
}