[백준] 14496 그대, 그머가 되어

14496번: 그대, 그머가 되어

 

boj.kr

풀이

각 글자를 정점이라고 생각하고 그래프를 만든 뒤, 최단 경로를 찾아주면 되는 문제이다. 다익스트라 알고리즘을 사용하면 어렵지 않게 해결할 수 있다.

코드

C++

#include <iostream>
#include <queue>
#include <vector>
using namespace std;

const int INF = 1e9;
int a, b, n, m;
vector<vector<int>> adj;
vector<int> dist;
vector<bool> visited;

void dijkstra(int start) {
    priority_queue<pair<int, int>> pq;
    pq.push({ 0, start });
    dist[start] = 0;
    visited[start] = true;

    while (!pq.empty()) {
        int now_dist = pq.top().first;
        int now = pq.top().second;
        pq.pop();

        if (now_dist > dist[now]) continue;

        for (int i : adj[now]) {
            int cost = now_dist + 1;
            if (cost < dist[i]) {
                dist[i] = cost;
                pq.push({ cost, i });
            }
        }
    }
}

int main() {
    ios_base::sync_with_stdio(0);
    cin.tie(0);

    cin >> a >> b;
    cin >> n >> m;
    adj = vector<vector<int>>(n + 1);
    dist = vector<int>(n + 1, INF);
    visited = vector<bool>(n + 1, false);

    for (int i = 0; i < m; i++) {
        int c1, c2;
        cin >> c1 >> c2;
        adj[c1].push_back(c2);
        adj[c2].push_back(c1);
    }

    dijkstra(a);
    if (dist[b] == INF) cout << "-1\n";
    else cout << dist[b] << '\n';
    return 0;
}

Python3

import sys
import heapq

INF = 1e9
input = sys.stdin.readline
a, b = map(int, input().rstrip().split())
n, m = map(int, input().rstrip().split())

adj = [[] for _ in range(n + 1)]
distance = [INF] * (n + 1)
visited = [False] * (n + 1)

for _ in range(m):
    c1, c2 = map(int, input().rstrip().split())
    adj[c1].append(c2)
    adj[c2].append(c1)


def dijkstra(start):
    q = []
    heapq.heappush(q, (0, start))
    distance[start] = 0
    visited[start] = True

    while q:
        dist, now = heapq.heappop(q)

        if distance[now] < dist:
            continue

        for i in adj[now]:
            cost = dist + 1
            if cost < distance[i]:
                distance[i] = cost
                heapq.heappush(q, (cost, i))


dijkstra(a)

if distance[b] == INF:
    print(-1)
else:
    print(distance[b])