## Solución al problema número 318 de AceptaelReto - 318.

Cualquier duda no dudes en contactar.

``````#include <bits/stdc++.h>
#define INF 0x3F3F3F3F
using namespace std;

const int MAXN = 1005;

struct edge{
int from, to, weight;
edge(){}
edge(int a, int b, int c){
from = a;
to = b;
weight = c;
}
};

struct state{
int node, dist;
state(){}
state(int a, int b){
node = a; dist = b;
}
bool operator<(const state &other)const{
return other.dist < dist;
}
};

vector<edge> graph[MAXN];
int dist[MAXN];

int a=1, b=3;
int N,E;

int dijkstra(int start, int end){
dist[start] = 0;
priority_queue<state> pq;
pq.push(state(start, 0));
while(!pq.empty()){
state cur = pq.top(); pq.pop();
if(dist[cur.node] < cur.dist) continue;
if(cur.node == end) return cur.dist;
for(int i=0;i<graph[cur.node].size();i++){
int dest = graph[cur.node][i].to;
int wht = graph[cur.node][i].weight + cur.dist;
if(dist[dest] <= wht) continue;
dist[dest] = wht;
pq.push(state(dest, wht));
}
}
return -1;
}
int main(){
while(scanf("%d",&N)!=EOF)
{
int arr[N];
for(int i =0; i<N;i++) cin>>arr[i];
scanf("%d",&E);
memset(dist,INF,sizeof(dist));
for(int i=0;i<=N;i++) { graph[i].clear(); } // limpia el grafo
for(int i=0;i<E;i++){
int from, to, weight; scanf("%d %d %d",&from, &to, &weight);
to--; from--;
graph[from].push_back(edge(from,to,weight+arr[to]));
}
int res = dijkstra(0,N-1);
if (res==-1) printf("IMPOSIBLE\n");
else printf("%d\n",res+arr[0]);
}
return 0;
}
``````