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Commit a9430c2

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Add Solution for shortestpath1 [OpenKattis]
1 parent 48e25ae commit a9430c2

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4 files changed

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‎OpenKattis/shortestpath1/README.md

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<img src="problem.png" />

‎OpenKattis/shortestpath1/problem.png

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‎OpenKattis/shortestpath1/solution.py

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import sys
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import io
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import os
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from collections import defaultdict
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from queue import PriorityQueue
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input = io.BytesIO(os.read(0,os.fstat(0).st_size)).readline
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while True:
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n, m, q, s = map(int, input().split())
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if (n + m + q + s) == 0:
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break
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arr = defaultdict(lambda: [])
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for i in range(m):
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u, v, w = map(int, input().split())
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arr[u].append((w, v))
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distance = defaultdict(lambda: 2e9)
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visited = defaultdict(lambda: False)
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short_path = PriorityQueue(maxsize=m)
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distance[s] = 0;
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short_path.put((0, s))
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while not short_path.empty():
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node = short_path.get()[1]
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if visited[node]: continue
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visited[node] = True
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for w, n in arr[node]:
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if distance[n] > w + distance[node]:
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distance[n] = w + distance[node]
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short_path.put((distance[n], n))
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for i in range(q):
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query = int(input())
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if distance[query] == 2e9:
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sys.stdout.write("Impossible\n")
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sys.stdout.flush()
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else:
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sys.stdout.write(str(distance[query]) + '\n')
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sys.stdout.flush()
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sys.stdout.write('\n')
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sys.stdout.flush()

‎OpenKattis/shortestpath1/soution.cpp

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#include<bits/stdc++.h>
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#define INF 99999999
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using namespace std;
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struct edge
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{
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int first;
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int second;
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edge(){}
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edge(int f, int s){
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first = f;
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second = s;
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}
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bool operator<(edge e) const{
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return first > e.first;
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}
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};
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bitset<10000+9> visited;
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int main(){
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ios_base::sync_with_stdio(false);
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cin.tie(NULL);
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int n, m, q, s, u, v, w;
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while(cin >> n >> m >> q >> s){
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if ((n + m + q + s) == 0)
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break;
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vector<edge> arr[n+1];
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for(int i = 0; i < m; i++){
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cin >> u >> v >> w;
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arr[u].push_back(edge(w, v));
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}
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vector<int> dist(n+9, INF);
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dist[s] = 0;
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priority_queue<edge> short_path;
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visited.reset();
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short_path.push(edge(0, s));
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while(!short_path.empty()){
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edge data = short_path.top();
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short_path.pop();
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int node = data.second;
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if (visited[node]) continue;
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visited.set(node);
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for(auto p: arr[node]) {
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if (dist[p.second] > (dist[node] + p.first)){
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dist[p.second] = dist[node] + p.first;
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short_path.push(edge(dist[p.second], p.second));
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}
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}
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}
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int in;
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for (int i = 0; i < q; i++){
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cin >> in;
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if(dist[in] == INF)
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cout << "Impossible\n";
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else
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cout << dist[in] << "\n";
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}
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cout << "\n";
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}
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}

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