Submission #83195

#	Time	Username	Problem	Language	Result	Execution time	Memory
83195		RezwanArefin01	Beads and wires (APIO14_beads)	C++17	100 / 100	472 ms	38024 KiB

beads

///usr/bin/g++ -O2 $0 -o ${0%.cpp} && echo "----------" && ./${0%.cpp}; exit;
#include <bits/stdc++.h>
using namespace std;

typedef long long ll; 
typedef pair<ll, int> ii;

const int N = 2e5 + 10; 
vector<int> adj[N], cost[N]; 
ll S[N], M[N], ans; 
int n, pcost[N]; 

void calc(int u, int par) {
    for(int i = 0; i < adj[u].size(); i++) {
        int v = adj[u][i], c = cost[u][i];
        if(v == par) continue; 
        pcost[v] = c; calc(v, u); 
        S[u] += max(S[v], M[v]); 
    }
    for(int v : adj[u]) if(v - par) {
        M[u] = max(M[u], S[u] - max(S[v], M[v]) + S[v]  + pcost[u] + pcost[v]); 
    }
}

void solve(int u, int par) {
    ans = max(ans, S[u]); 
    vector<ii> l = {{-1e18, 0}};
    for(int i = 0; i < adj[u].size(); i++) {
        int v = adj[u][i], c = cost[u][i];
        l.push_back({-max(S[v], M[v]) + S[v] + c, v}); 
    } sort(l.begin(), l.end(), greater<ii>()); 
    for(int i = 0; i < adj[u].size(); i++) {
        int v = adj[u][i], c = cost[u][i]; 
        if(v == par) continue; 
        ll a = S[u], b = S[v], C = M[u], d = M[v];
        S[u] -= max(S[v], M[v]); 
        M[u] = S[u] + c + (l[0].second == v ? l[1].first : l[0].first); 
        S[v] += max(S[u], M[u]); 
        solve(v, u); 
        S[u] = a, S[v] = b, M[u] = C, M[v] = d; 
    }
}

int main() {
    int n; scanf("%d", &n);
    for(int i = 1; i < n; i++) {
        int u, v, c;
        scanf("%d %d %d", &u, &v, &c); 
        adj[u].push_back(v); 
        adj[v].push_back(u); 
        cost[u].push_back(c);
        cost[v].push_back(c); 
    }
    calc(1, 0); 
    solve(1, 0); 
    printf("%lld\n", ans); 
}

Compilation message (stderr)

beads.cpp: In function 'void calc(int, int)':
beads.cpp:14:22: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
     for(int i = 0; i < adj[u].size(); i++) {
                    ~~^~~~~~~~~~~~~~~
beads.cpp: In function 'void solve(int, int)':
beads.cpp:28:22: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
     for(int i = 0; i < adj[u].size(); i++) {
                    ~~^~~~~~~~~~~~~~~
beads.cpp:32:22: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
     for(int i = 0; i < adj[u].size(); i++) {
                    ~~^~~~~~~~~~~~~~~
beads.cpp: In function 'int main()':
beads.cpp:45:17: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
     int n; scanf("%d", &n);
            ~~~~~^~~~~~~~~~
beads.cpp:48:14: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
         scanf("%d %d %d", &u, &v, &c); 
         ~~~~~^~~~~~~~~~~~~~~~~~~~~~~~

• Subtask 1: 13 / 13
• Subtask 2: 15 / 15
• Subtask 3: 29 / 29
• Subtask 4: 43 / 43