Submission #1261007

#	Time	Username	Problem	Language	Result	Execution time	Memory
1261007		vominhhuy123	관광 (NOI14_sightseeing)	C++20	15 / 25	1957 ms	98932 KiB

sightseeing

#include <bits/stdc++.h>
#define fto(i, a, b) for (int i = (a); i <= (b); ++i)
#define fdto(i, b, a) for (int i = (b); i >= (a); --i)
#define N 500005
#define mod 1000000007

using namespace std;

int n, m, k, visited[N], ans[N], p[N], sz[N];
vector<pair<int, int>> edge[N];
vector<int> adj[N];

int root(int u) {
    return p[u] != u ? p[u] = root(p[u]) : u;
}

void dfs(int u, int val) {
    visited[u] = 1;
    ans[u] = val;
    for (int v : adj[u]) if (!visited[v]) dfs(v, val);
}

bool join(int u, int v) {
    u = root(u), v = root(v);
    if (u == v) return false;
    if (sz[v] > sz[u]) swap(u, v);
    sz[u] += sz[v];
    p[v] = u;
    return true;
}

int main() {
    ios_base::sync_with_stdio(0); cin.tie(0);
    if (fopen("test.inp", "r")) {
        freopen("test.inp", "r", stdin);
        freopen("test.out", "w", stdout);
    }
    scanf("%d %d %d", &n, &m, &k);
    fto(i, 1, n) p[i] = i, sz[i] = 1;
    fto(i, 1, m) {
        int u, v, w;
        scanf("%d %d %d", &u, &v, &w);
        edge[w].emplace_back(u, v);
    }
    fto(i, 1, n) ans[i] = -1;
    fdto(w, 100000, 0) {
        for (pair<int, int> p : edge[w]) {
            int u = p.first, v = p.second;
            if (join(u, v)) {
                adj[u].push_back(v);
                adj[v].push_back(u);
            }
            if (root(1) == root(u) && ans[u] == -1) dfs(u, w);
            if (root(1) == root(v) && ans[v] == -1) dfs(v, w);
        }
    }
    while (k--) {
        int x;
        scanf("%d", &x);
        printf("%d\n", ans[x]);
    }
}

Compilation message (stderr)

sightseeing.cpp: In function 'int main()':
sightseeing.cpp:35:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   35 |         freopen("test.inp", "r", stdin);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~
sightseeing.cpp:36:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   36 |         freopen("test.out", "w", stdout);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~
sightseeing.cpp:38:10: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
   38 |     scanf("%d %d %d", &n, &m, &k);
      |     ~~~~~^~~~~~~~~~~~~~~~~~~~~~~~
sightseeing.cpp:42:14: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
   42 |         scanf("%d %d %d", &u, &v, &w);
      |         ~~~~~^~~~~~~~~~~~~~~~~~~~~~~~
sightseeing.cpp:59:14: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
   59 |         scanf("%d", &x);
      |         ~~~~~^~~~~~~~~~

• Subtask 1: 4 / 4
• Subtask 2: 5 / 5
• Subtask 3: 6 / 6
• Subtask 4: 0 / 10