Submission #1125632

#	Time	Username	Problem	Language	Result	Execution time	Memory
1125632		Kerim	Pipes (BOI13_pipes)	C++20	0 / 100	3 ms	2784 KiB

pipes

#include "bits/stdc++.h"
#define ff first
#define ss second
#define ll long long

using namespace std;
const int N = 1e5+5;
vector<pair<int,int> > adj[N];
pair<int, int> par[N];
vector<int> order;
ll a[N], ans[N];
void dfs(int nd, int pr){
    for (auto [to, ind]: adj[nd]){
        if (to == pr)
            continue;
        par[to] = {nd, ind};
        dfs(to, nd);
    }
    order.push_back(nd);
}
int main(){
    freopen("file.in", "r", stdin);
    int n, m;
    scanf("%d%d", &n, &m);
    assert(m == n-1);
    for (int i = 1; i <= n; i++)
        scanf("%lld", a+i);
    for (int i = 1; i <= m; i++){
        int u, v;
        scanf("%d%d", &u, &v);
        adj[u].push_back({v, i});
        adj[v].push_back({u, i});
    }
    dfs(1, -1);
    for (auto x: order){
        ans[par[x].ss] = a[x] * 2;
        a[par[x].ff] -= a[x];
        x = par[x].ff;
    }
    if (!a[1]){
        for (int i = 1; i <= m; i++)
            printf("%lld\n", ans[i]);
    }
    else
        puts("0");
    return 0;
}

Compilation message (stderr)

pipes.cpp: In function 'int main()':
pipes.cpp:22:12: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   22 |     freopen("file.in", "r", stdin);
      |     ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~
pipes.cpp:24:10: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
   24 |     scanf("%d%d", &n, &m);
      |     ~~~~~^~~~~~~~~~~~~~~~
pipes.cpp:27:14: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
   27 |         scanf("%lld", a+i);
      |         ~~~~~^~~~~~~~~~~~~
pipes.cpp:30:14: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
   30 |         scanf("%d%d", &u, &v);
      |         ~~~~~^~~~~~~~~~~~~~~~

• Subtask 1: 0 / 30
• Subtask 2: 0 / 70