D. Navigation System-（最短路+BFS）

总结

这题的我自己总结来，就是话贼多，我这种语文水平不好，英语能力又极差的人，当时读偏题了，想了好久，越想越不对，后面问清题意后，就好做多了，多错题意害死人。

解析

就是判断两点间可否满足min or max
min：满足条件不计数：dis[u]=1+dis[v]
max：满足条件不计数：dis[u]=1+dis[v]，且u的其他所有相邻结点存在到t的距离+1 == dis[u]

题目链接

/*
                ____________    ______________       __
               / _________  /\ /_____   _____/\     / /\
              / /\       / /  \\    /  /\    \ \   / /  \
             / /  \_____/ /   / \__/  /  \____\/  / /   /
            / /   /    / /   /    /  /   /       / /   /
           / /   /    / /   /    /  /   /       / /   /
          / /   /    / /   /    /  /   /       / /   /
         / /___/____/ /   /    /  /   /       / /___/________
        /____________/   /    /__/   /       /______________/\
        \            \  /     \  \  /        \              \ \
         \____________\/       \__\/          \______________\/
           ___       ___               ___    __________
          /  /\     /  /\             /  /\  /_______  /\
         /  /__\___/  /  \           /  /  \ \      /  /  \
        /____    ____/   /          /  /   /  \____/  /   /
        \   /   /\   \  /          /  /   /       /  /   /
         \_/   /  \___\/ ___      /  /   /       /  /   /
          /   /   /     /  /\    /  /   /       /  /   /
         /   /   /     /  /__\__/  /   /       /  /___/____
        /___/   /     /___________/   /       /___________/\
        \   \  /      \           \  /        \           \ \
         \___\/        \___________\/          \___________\/

          A CODE OF CBOY

*/
#include<bits/stdc++.h>
//typedef long long ll;
//#define ull       unsigned long long
//#define int       long long
#define F           first
#define S           second
#define endl        "\n"//<<flush
#define eps         1e-6
#define lowbit(x)   (x&(-x))
#define PI          acos(-1.0)
#define inf         0x3f3f3f3f
#define MAXN        0x7fffffff
#define INF         0x3f3f3f3f3f3f3f3f
#define pa          pair<int,int>
#define ferma(a,b)  pow(a,b-2)
#define pb          push_back
#define all(x)      x.begin(),x.end()
#define memset(a,b) memset(a,b,sizeof(a));
#define IOS         ios::sync_with_stdio(false),cin.tie(0),cout.tie(0);
using namespace std;
void file()
{
#ifdef ONLINE_JUDGE
#else
    freopen("cin.txt","r",stdin);
    //  freopen("cout.txt","w",stdout);
#endif
}
const int N=2e5+5;
vector<int>G[N],GT[N];
int vis[N],dis[N];
void bfs(int x)
{
    queue<int>que;
    que.push(x);
    vis[x]=true;
    while(!que.empty())
    {
        int pos=que.front();
        que.pop();
        for(auto it:G[pos])
        {
            if(vis[it])
                continue;
            vis[it]=true;
            que.push(it);
            dis[it]=dis[pos]+1;
        }
    }
}
signed main()
{
    IOS;
    //file();
    int n,m;
    cin>>n>>m;
    while(m--)
    {
        int x,y;
        cin>>x>>y;
        GT[x].pb(y);
        G[y].pb(x);
    }
    int k;
    cin>>k;
    vector<int>vec(k),ans(2);
    for(auto &it:vec)
        cin>>it;
    bfs(vec[k-1]);
    for(int i=0;i<k-1;i++)
    {
        vector<int>flag(2);
        int v=vec[i];
        for(auto u:GT[v])
        {
            if(1+dis[u]==dis[v]&&u==vec[i+1])
                flag[0]++;
            if(1+dis[u]==dis[v]&&u!=vec[i+1])
                flag[1]++;
        }
        ans[0]+=(flag[0]?0:1);
        ans[1]+=(flag[0]&&flag[1]==0?0:1);
    }
    cout<<ans[0]<<" "<<ans[1]<<endl;
    return 0;
}