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| #include <bits/stdc++.h>
#define pii pair<int, int>
#define FAST_IO ios_base::sync_with_stdio(0);cin.tie(0);cout.tie(0);
using namespace std;
const int INF = 0x3f3f3f3f;
const int Maxn = 1e3+5;
struct node{
int to, w;
};
vector <node> V[Maxn];
int n, m, k;
int Dis[Maxn], Vis[Maxn];
priority_queue <pii, vector<pii>, greater<pii> > q;
int Dij(int mid)
{
memset(Vis, 0, sizeof(Vis));
memset(Dis, INF, sizeof(Dis));
Dis[1] = 0;
q.push(pii(0,1));
while(q.size())
{
int x = q.top().second;
q.pop();
if(Vis[x]) continue;
Vis[x] = 1;
for(int i = 0; i < V[x].size(); i++)
{
int y = V[x][i].to, w = (V[x][i].w >= mid);
if(Dis[y] > Dis[x] + w){
Dis[y] = Dis[x] + w;
q.push(pii(Dis[y],y));
}
}
}
return Dis[n];
}
int main()
{
FAST_IO;
while(cin >> n >> m >> k)
{
int x, y, z; int Max = 0;
for(int i = 0; i <= n; i++) V[i].clear();
for(int i = 0; i < m; i++)
{
cin >> x >> y >> z;
Max = max(Max, z);
V[x].push_back((node){y, z});
V[y].push_back((node){x, z});
}
int ans = 0, l = 0, r = Max;
while(l <= r)
{
int mid = (l+r) / 2;
if(Dij(mid) <= k){
r = mid - 1;
}
else {
ans = mid;
l = mid + 1;
}
}
if(l > Max) cout << -1 << endl;
else cout << ans << endl;
}
return 0;
}
|
