Submission #1108480

#	Time	Username	Problem	Language	Result	Execution time	Memory
1108480		crafticat	Dynamic Diameter (CEOI19_diameter)	C++17	11 / 100	5072 ms	4804 KiB

diameter

#include <bits/stdc++.h>

using namespace std;

using ll = long long;
template<typename T>
using V = vector<T>;
using vi = V<int>;
using vb = V<bool>;
using pi = pair<int,int>;

#define F0R(i,n) for (int i = 0; i < n;i++)
#define FOR(i, j, n) for(int i = j; i < n;i++)
#define ckmin(x,y) x = min(x,y)
#define f first
#define s second
#define pb push_back
#define sor(a,b) min(a,b), max(a,b)

vi dx = {0,1,0,-1};
vi dy = {1,0,-1,0};

V<V<V<pi>>> grid;
V<vi> exists;
V<vb> visited;

V<V<int>> g;
map<pi, int> weights;
vi dp;

void dfs(int x, int p, int d) {
    dp[x] = d;

    for (auto c : g[x]) {
        if (c ==p) continue;
        dfs(c,x, d + weights[{sor(c,x)}]);
    }
}

int far(int n) {
    int sel = 1, dist = 0;
    FOR(i, 1, n + 1) {
        if (dp[i] > dp[sel]) sel = i;
    }
    return sel;
}

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

    int n, q, cMAX; cin >> n >> q >> cMAX;
    g.resize(n + 1);

    V<pi> edges(n);

    F0R(i, n - 1) {
        int a, b, c; cin >> a >> b >> c;
        g[a].pb(b);
        g[b].pb(a);
        edges[i] = {a,b};
        weights[{sor(a, b)}] = c;
    }

    dp.resize(n + 1);
    int last = 0;
    F0R(i, q) {
        int e, c; cin >> e >> c;
        e = (e + last) % (n - 1);
        c = (last + c) % (cMAX);

        auto [a,b] = edges[e];
        weights[{sor(a,b)}] = c;

        dfs(1, -1, 0);
        int pa = far(n);
        dfs(pa, -1, 0);
        int pa2 = far(n);
        int results = dp[pa2];
        cout << results << "\n";
        last = results;
    }

    return 0;
}

Compilation message (stderr)

diameter.cpp: In function 'int far(int)':
diameter.cpp:41:18: warning: unused variable 'dist' [-Wunused-variable]
   41 |     int sel = 1, dist = 0;
      |                  ^~~~

• Subtask 1: 11 / 11
• Subtask 2: 0 / 13
• Subtask 3: 0 / 7
• Subtask 4: 0 / 18
• Subtask 5: 0 / 24
• Subtask 6: 0 / 27