[SSL] 1129 alphabetical order

[SSL] 1129 alphabetical order

Time Limit:1000MS
Memory Limit:65536K

Description

Enter a series of letters that are less than the relationship and output the final order. For
example, enter: A

Input

Two integers nm (2<=n<=26) (end when n=m=0)
m line "less than relation" (only less than<)

Output

If the last sorting exists, output: Sorted sequence determined after xxx relations: yyy...y.
If the sorting cannot be completed, output: Sorted sequence cannot be determined.
If there is a contradiction after the xth relationship (such as A＜B,B＜C, C＜A) Output: Inconsistency found after x relations.

Sample Input

4 6
A<B
A<C
B<C
C<D
B<D
A<B
3 2
A<B
B<A
26 1
A<Z
0 0

Sample Output

Sorted sequence determined after 4 relations: ABCD.
Inconsistency found after 2 relations.
Sorted sequence cannot be determined.

Hint

uncle

Ideas

It is a multi-group data version sorted by P1347 in 【Luogu】 , the initial value should be set each time.
For each input, do a topological sort.
Conflicts output
. Inconsistency found after x relations
sorting the only output
Sorted sequence determined after xxx relations: yyy ... y.

Code

#include<iostream>
#include<cstdio>
#include<queue>
#include<cstring>
using namespace std;
long long ans[610],tot,n,m,head[610],ins[610],inst[610],q[610];
char str[610];
string answer;
struct jgt
{
    
    
	long long x,y,nxt;
}f[610];
int topsort()
{
    
    
	long long i,l,r=0;
	for(i=1;i<=n;i++)
		if(!inst[i])
		{
    
    
			q[++r]=i;
			ans[i]=1;
		}
	for(l=1;l<=r;l++)
	{
    
    
		for(i=head[q[l]];i;i=f[i].nxt)//更新入度 
		{
    
    
			inst[f[i].y]--;
			ans[f[i].y]=max(ans[f[i].y],ans[q[l]]+1);
			if(!inst[f[i].y])//当能够到达这个点的所有点都遍历过后将这个点加入队列
				q[++r]=f[i].y;
		}
	}
	if(r<n)//矛盾 
		return 0;
	if(ans[q[r]]==n)//排序唯一 
	{
    
    
		for(i=1;i<=r;i++)
			answer+=char(q[i]+'A'-1);
		return 1;
	}
	return -1;
}
int main()
{
    
    
	long long i,j,t;
	bool light;
	scanf("%lld%lld",&n,&m);
	while(n||m)
	{
    
    
		tot=0;
		light=1;
		answer="";
		memset(ins,0,sizeof(ins));
		memset(head,0,sizeof(head));
		memset(ans,0,sizeof(ans));
		memset(inst,0,sizeof(inst));
		memset(q,0,sizeof(q));
		for(i=1;i<=m;i++)
		{
    
    
			tot++;
			scanf("%s",&str);
			f[tot].x=str[0]-'A'+1;
			f[tot].y=str[2]-'A'+1;
			f[tot].nxt=head[f[tot].x];
			head[f[tot].x]=tot;
			ins[f[tot].y]++;
			for(j=1;j<=n;j++)
				inst[j]=ins[j];
			t=topsort();
			if(t==0)
			{
    
    
				printf("Inconsistency found after %lld relations.\n",i);
				light=0;
				for(i++;i<=m;i++)scanf("%*s");
			}
			if(t==1)
			{
    
    
				printf("Sorted sequence determined after %lld relations: %s.\n",i,answer.c_str());
				light=0;
				for(i++;i<=m;i++)scanf("%*s");
			}
		}
		if(light)
			printf("Sorted sequence cannot be determined.\n");
		scanf("%lld%lld",&n,&m);
	} 
	return 0;
}