Submission #1163779

#	TimeUTC-0	Username	Problem	Language	Result	Execution time	Memory
1163779	2025-03-08 13:03:11	ChottuF	Railway (BOI17_railway)	C++20	100 / 100	79 ms	28360 KiB

railway

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#include <bits/stdc++.h>
using namespace std;
 
const int MAXN = 100005;
const int MAXH = 18; // since n <= 1e5, log2(n) < 18
int n, m, k;
vector<vector<int>> adj;
int depth[MAXN], parentArr[MAXN];
int up[MAXH][MAXN];
int tin[MAXN], tout[MAXN], timer = 0;
 
// DFS to compute tin/tout, depth and immediate parent.
void dfs(int u, int p, int d) {
    depth[u] = d;
    parentArr[u] = p;
    tin[u] = ++timer;
    up[0][u] = p;
    for (int v : adj[u]) {
        if (v == p) continue;
        dfs(v, u, d+1);
    }
    tout[u] = timer;
}
 
// Standard binary lifting LCA.
int lca(int a, int b) {
    if(depth[a] < depth[b])
        swap(a, b);
    int d = depth[a] - depth[b];
 
 
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