宽搜

#include<bits/stdc++.h>
using namespace std;
int n,x,y;
int r;
bool h[111];
struct node
{
	int x,st;
};
vector<int> q[111];
queue<node> p;
void bfs()
{
	int st;
	p.push({x,0});
	h[x]=1;
	while(!p.empty())
	{
		x=p.front().x;
		st=p.front().st;
		p.pop();
		for(int i=0;i<q[x].size();i++)
		{
			if(!h[q[x][i]])
			{
				h[q[x][i]]=1;
				if(q[x][i]==y) 
				{
					cout<<st<<endl;
					return;
				}
				p.push({q[x][i],st+1});
			}
		}
	}
}
int main()
{
	//freopen("relationship.in","r",stdin);
	//freopen("relationship.out","w",stdout);
	cin>>n>>x>>y;
	for(int i=1;i<=n;i++)
	{
		for(int j=1;j<=n;j++)
		{
			cin>>r;
			if(r)
			{
				q[i].push_back(j);
			}
		}
	}
	if(x==y) 
	{
		cout<<0<<endl;
		return 0;
	}
	bfs();
	return 0;
}