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BusRoutes.cpp
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BusRoutes.cpp
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#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
using namespace __gnu_pbds;
using namespace std;
#define ff first
#define ss second
#define endl "\n"
#define ll long long
#define ld long double
#define loop(a, b, c) for(ll (a) = (b); (a)<=(c); (a)++)
#define looprev(a, b, c) for(ll (a) = (b); (a)>=(c); (a)--)
#define pb push_back
#define mp make_pair
#define pii pair<ll, ll>
#define vi vector<ll>
#define mii map<ll, ll>
#define ump unordered_map<ll, ll>
#define pqb priority_queue<ll>
#define pqs priority_queue<int, vi, greater<ll> >
#define setbits(x) __builtin_popcountll(x)
#define zrobits(x) __builtin_ctzll(x)
#define mod 1000000007
#define inf 1e18
#define ps(x, y) fixed<<setprecision(y)<<x
#define mk(arr,n,type) type *arr = new type[n];
#define w(t) int x; cin>>x; while(x--)
// mt19937 rng(chrono::steady_clock::now,time_since_epoch(),count());
typedef tree<pair<int, int>, null_type, less<pair<int, int>>, rb_tree_tag, tree_order_statistics_node_update> pbds;
void file_i_o(){
ios_base::sync_with_stdio(0);
cin.tie(0);
cout.tie(0);
/* #ifndef ONLINE_JUDGE
freopen("input.txt", "r", stdin);
freopen("output.txt", "w", stdout);
#endif */
}
class Solution {
public:
int numBusesToDestination(vector<vector<int>>& routes, int source, int target) {
unordered_map<int, unordered_set<int>> stop_routes;
for(int i = 0; i < routes.size(); i++) {
for(int j : routes[i])
stop_routes[j].insert(i);
}
queue<pair<int, int>> to_visit;
to_visit.push({source, 0});
unordered_set<int> stops_visited = {source};
while(not to_visit.empty()) {
int stop = to_visit.front().first;
int bus_n = to_visit.front().second;
if(stop == target) {
return bus_n;
}
to_visit.pop();
for(const auto& route : stop_routes[stop]) {
for(const auto& next_stop : routes[route]) {
auto it = stops_visited.insert(next_stop);
if(it.second)
to_visit.push({next_stop, bus_n+1});
}
routes[route].clear ();
}
}
return -1;
}
};
int main(int argc, char const *argv[]) {
file_i_o();
clock_t start, end;
start = clock();
w(t){
/* Write Code Here */
}
end = clock();
double time_taken=double(end-start)/double(CLOCKS_PER_SEC);
cerr<<"\nTime : "<<fixed<<time_taken<<setprecision(5)<<" s \n";
cerr<<"\n"<< "Coded By : S!r Black-D3vil" <<"\n";
return 0;
}