ソースコード
// 基本テンプレート
#include <iostream>
#include <iomanip>
#include <cstdio>
#include <string>
#include <cstring>
#include <deque>
#include <list>
#include <queue>
#include <stack>
#include <vector>
#include <utility>
#include <algorithm>
#include <map>
#include <set>
#include <complex>
#include <cmath>
#include <limits>
#include <cfloat>
#include <climits>
#include <ctime>
#include <cassert>
#include <numeric>
#include <fstream>
#include <functional>
using namespace std;
#define rep(i,a,n) for(int (i)=(a); (i)<(n); (i)++)
#define repq(i,a,n) for(int (i)=(a); (i)<=(n); (i)++)
#define repr(i,a,n) for(int (i)=(a); (i)>=(n); (i)--)
#define debug(...) fprintf(stderr, __VA_ARGS__)
#define int long long int
template<typename T> void chmax(T &a, T b) {a = max(a, b);}
template<typename T> void chmin(T &a, T b) {a = min(a, b);}
template<typename T> void chadd(T &a, T b) {a = a + b;}
typedef pair<int, int> pii;
typedef long long ll;
int dx[] = {0, 0, 1, -1};
int dy[] = {1, -1, 0, 0};
const ll INF = 1001001001001001LL;
const ll MOD = 1000000007LL;
int N, M, K;
int visited[100010], dist[100010];
using Graph = vector< vector<pii> >;
struct Elem {
int pos, cost;
bool operator<(const Elem &e) const {
return cost > e.cost;
}
};
signed main() {
scanf("%lld%lld%lld", &N, &M, &K);
Graph G(N);
for(int i=0; i<M; i++) {
int a, b, c; scanf("%lld%lld%lld", &a, &b, &c);
a--; b--;
G[a].push_back(make_pair(b, c));
G[b].push_back(make_pair(a, c));
}
while(K--) {
int source, max_d;
scanf("%lld%lld", &source, &max_d);
source--;
priority_queue<Elem> que;
que.push(Elem{source, 0});
visited[source] = true;
while(que.size()) {
Elem cur = que.top(); que.pop();
int u = cur.pos, cost = cur.cost;
if(dist[u] < cost) continue;
for(auto e : G[u]) {
int v = e.first, weight = e.second;
int n_dist = cost + weight;
if(n_dist > max_d) continue;
if(dist[v] > n_dist) continue;
if(visited[v]) continue;
visited[v] = true;
dist[v] = n_dist;
que.push(Elem{v, n_dist});
}
}
}
int ans = 0;
for(int i=0; i<N; i++) if(visited[i]) ans++;
printf("%lld\n", ans);
return 0;
}