题解

#include <bits/stdc++.h>
using namespace std;

template<typename T>
void read(T& FF) {
    T RR = 1;
    FF = 0;
    char c;
    cin>>c;
    for (; !isdigit(c); c = getchar())
        if (c == '-')
            RR = -1;
    for (; isdigit(c); c = getchar())
        FF = (FF << 1) + (FF << 3) + (c ^ 48);
    FF *= RR;
}

template<typename T>
void write(T x) {
    if (x < 0)
        putchar('-'), x *= -1;
    if (x > 9)
        write(x / 10);
    putchar(x % 10 + 48);
}

const int MAXN = 100010;
vector<int> v[MAXN];
int ji[MAXN], ou[MAXN];

void bfs() {
    memset(ji, 0x3f, sizeof(ji));
    memset(ou, 0x3f, sizeof(ou));
    queue<pair<int, int>> q;
    for (int i = 0; i < v[1].size(); i++) {
        ji[v[1][i]] = 1;
        q.push(make_pair(v[1][i], 1));
    }
    while (!q.empty()) {
        int x = q.front().first, y = q.front().second;
        for (int i = 0; i < v[x].size(); i++) {
            if (y % 2 == 1) {
                if (y + 1 < ou[v[x][i]]) {
                    ou[v[x][i]] = y + 1;
                    q.push(make_pair(v[x][i], y + 1));
                }
            } else {
                if (y + 1 < ji[v[x][i]]) {
                    ji[v[x][i]] = y + 1;
                    q.push(make_pair(v[x][i], y + 1));
                }
            }
        }
        q.pop();
    }
}

int main() {
    int n, m, q;
    read(n);
    read(m);
    read(q);
    for (int i = 1; i <= m; i++) {
        int x, y;
        read(x);
        read(y);
        v[x].push_back(y);
        v[y].push_back(x);
    }
    bfs();
    while (q--) {
        int x, y;
        read(x);
        read(y);
        if (y % 2 == 0) {
            if (ou[x] > y)
                cout<<"No"<<'\n';
            else
                cout<<"Yes"<<'\n';
        } else {
            if (ji[x] > y)
                cout<<"No"<<'\n';
            else
                cout<<"Yes"<<'\n';
        }
    }
    return 0;
}