delete pics to save space

1.1347.cpp

@@ -0,0 +1,60 @@
+#include<cstdio>
+#include<algorithm>
+#include<cassert>
+#include<vector>
+#include<cstdlib>
+#include<cstring>
+#include<stack>
+using namespace std;
+int n,m;
+struct Edge { int v,id; };
+vector<Edge> G[30];
+inline void AddEdge(int u,int v,int id) { G[u].push_back((Edge){v,id}); }
+inline void solve(int id)
+{
+	static int in[30],res[30];
+	memset(in,0,sizeof(in));
+	for(int i=1;i<=n;i++) for(Edge it:G[i]) if(it.id<=id) in[it.v]++;
+	stack<int> stk;
+	for(int i=1;i<=n;i++) if(!in[i]) stk.push(i);
+	bool unsure=0; int cnt=0;
+	while(stk.size())
+	{
+		unsure|=(stk.size()>=2);
+		int u=res[cnt++]=stk.top(); stk.pop();
+		for(Edge it:G[u]) if(it.id<=id)
+		{
+			in[it.v]--;
+			if(!in[it.v]) stk.push(it.v);
+		}
+	}
+	for(int i=1;i<=n;i++) if(in[i])
+	{
+		printf("Inconsistency found after %d relations.\n",id);
+		exit(0);
+	}
+	if(unsure) return;
+	printf("Sorted sequence determined after %d relations: ",id);
+	for(int i=0;i<cnt;i++) putchar(res[i]-1+'A');
+	puts(".");
+	exit(0);
+}
+int main()
+{
+#ifdef local
+	freopen("pro.in","r",stdin);
+#endif
+	scanf("%d%d",&n,&m);
+	assert(m>=1);
+	assert(m<=n*(n-1));
+	for(int i=0;i<m;i++)
+	{
+		char s[10]; scanf("%s",s);
+		int u=s[0]-'A'+1,v=s[2]-'A'+1;
+		if(s[1]=='>') swap(u,v);
+		AddEdge(u,v,i+1);
+	}
+	for(int i=1;i<=m;i++) solve(i);
+	puts("Sorted sequence cannot be determined.");
+	return 0;
+}