Here you will find solutions of many problems on spoj. If you want solution of some problem which is not listed in blog or have doubt regarding any spoj problem (which i have solved) or any programming concept (data structure) you can mail me @ raj.nishant360@gmail.com
And my humble request to you all that don't copy the code only try to understand the logic and algorithm behind the code. I have started this because if you tried as hard as you can and still can't find any solution to the problem then you can refer to this.
You can read my answer how to start competitive programming CLICK HERE

Saturday, October 10, 2015

SHPATH-The Shortest Path

The Shortest Path

Given Below code is for shpath spoj or the shortest path spoj.



/*
===================================================
Name :- Nishant Raj
Email :- raj.nishant360@gmail.com
College :- Indian School of Mines
Branch :- Computer Science and Engineering
Time :- 08 September 2015 (Tuesday) 20:11
===================================================*/
#include <bits/stdc++.h>
#include <unordered_map>
using namespace std;
#define ll long long
#define pii pair < int , int >
#define pb push_back
#define mp make_pair
#define mod 1000000009
struct cmp
{
    bool operator()(const pair<int , int> &a , const pair<int , int> &b){
        return a.first > b.first;
    }
};
int main(){
    ios::sync_with_stdio(false);
    int t;
    cin>>t;
    while(t--){
        int n;
        cin>>n;
        string s;
        vector<int> graph[n+9];
        vector<vector<int> > cost(n+1 , vector<int>(n+1 , 0));
        map<string, int> map_name;
        for(int i = 1 ; i <= n ; i++){
            cin>>s;
            map_name[s] = i;
            int path , k , c;
            cin>>path;
            for(int j = 0 ; j < path ; j++){
                cin>>k>>c;
                graph[i].pb(k);
                cost[i][k] = c;
            }
        }
        int k;
        cin>>k;
        while(k--){
            char source_temp[12] , dest_temp[12];
            string source , dest;
            source.assign(source_temp);
            dest.assign(dest_temp);
            cin>>source>>dest;
            priority_queue<pii , vector<pii >, cmp > pq;
            ll dist[n+9];
            fill(dist , dist+n , INT_MAX-100000);
            int dist_num = map_name[dest] , source_num = map_name[source];
            dist[source_num] = 0;
            pq.push(mp(0 , source_num));
            while(!pq.empty()){
                int wt = pq.top().first;
                int node = pq.top().second;
                pq.pop();
                if(node == dist_num){
                    cout<<wt<<endl;
                    break;
                }
                for(auto it:graph[node]){
                    if(dist[it] > dist[node] + cost[node][it]){
                        dist[it] = dist[node] + cost[node][it];
                        pq.push(mp(dist[it] , it));
                    }
                }
            }
        }
    }
    
    return 0;
}