这题我本来想用floyd做，然后全WA

#include <bitset>
#include <cstdio>
#include <iostream>
#include <memory.h>
#include <vector>
using namespace std;
const int maxn=1145,inf=0x3F3F3F3F;
inline int read(){
    int sum=0,sign=1;
    char tmp=getchar();
    while(tmp<'0'||tmp>'9'){
        sign=tmp=='-'?-1:1;
        tmp=getchar();
    }
    while(tmp>='0'&&tmp<='9'){
        sum=(sum<<1)+(sum<<3)+tmp-'0';
        tmp=getchar();
    }
    return sum*sign;
}
bitset<maxn> calc[maxn][maxn];
int n,m,dist[maxn][maxn];
int main(){
    //freopen("LG6328.in","r",stdin);
    //freopen("LG6328.out","w",stdout);
    memset(dist,inf,sizeof(dist));
    n=read();
    for(int i=1;i<=n;i++){
        dist[i][i]=0;
    }
    m=read();
    int q=read();
    for(int i=0;i<m;i++){
        int x=read(),y=read();
        dist[x][y]=dist[y][x]=1;
    }
    for(int mid=1;mid<=n;mid++){
        for(int s=1;s<=n;s++){
            for(int t=1;t<=n;t++){
                if(dist[s][mid]+dist[mid][t]<dist[s][t]){
                    dist[s][t]=dist[t][s]=dist[s][mid]+dist[mid][t];
                }
            }
        }
    }
    for(int s=1;s<=n;s++){
        for(int t=1;t<=n;t++){
            if(dist[s][t]!=inf){
                calc[s][dist[s][t]].set(t,1);
            }
        }
        for(int d=1;d<=n;d++){
            calc[s][d]|=calc[s][d-1];
        }
    }
    while(q--){
        int a=read();
        bitset<maxn> rslt;
        rslt.reset();
        while(a--){
            int x=read(),y=read();
            if(y>n){
                y=n;
            }
            rslt|=calc[x][y];
        }
        cout<<rslt.count()<<endl;
    }
    return 0;
}

改成BFS就AC了

#include <bitset>
#include <cstdio>
#include <iostream>
#include <memory.h>
#include <queue>
#include <vector>
using namespace std;
const int maxn=1145,inf=0x3F3F3F3F;
inline int read(){
    int sum=0,sign=1;
    char tmp=getchar();
    while(tmp<'0'||tmp>'9'){
        sign=tmp=='-'?-1:1;
        tmp=getchar();
    }
    while(tmp>='0'&&tmp<='9'){
        sum=(sum<<1)+(sum<<3)+tmp-'0';
        tmp=getchar();
    }
    return sum*sign;
}
bitset<maxn> calc[maxn][maxn];
vector<int> graf[maxn];
queue<int> que;
int n,m,dist[maxn];
bool flags[maxn];
void bfs(int x){
    memset(flags,0,sizeof(flags));
    dist[x]=0;
    flags[x]=1;
    que.push(x);
    while(!que.empty()){
        int pos=que.front();
        que.pop();
        calc[x][dist[pos]].set(pos,1);
        for(unsigned int i=0;i<graf[pos].size();i++){
            if(flags[graf[pos][i]]){
                continue;
            }
            dist[graf[pos][i]]=dist[pos]+1;
            flags[graf[pos][i]]=1;
            que.push(graf[pos][i]);
        }
    }
    for(int i=1;i<=n;i++){
        calc[x][i]|=calc[x][i-1];
    }
}
int main(){
    //freopen("LG6328.in","r",stdin);
    //freopen("LG6328.out","w",stdout);
    n=read();
    m=read();
    int q=read();
    for(int i=0;i<m;i++){
        int x=read(),y=read();
        graf[x].push_back(y);
        graf[y].push_back(x);
    }
    for(int i=1;i<=n;i++){
        bfs(i);
    }
    bitset<maxn> rslt;
    while(q--){
        int a=read();
        rslt.reset();
        while(a--){
            int x=read(),y=read();
            if(y>n){
                y=n;
            }
            rslt|=calc[x][y];
        }
        cout<<rslt.count()<<endl;
    }
    return 0;
}

难道我floyd写假了？