Submission #699685

#	Time	Username	Problem	Language	Result	Execution time	Memory
699685		finn__	Pipes (BOI13_pipes)	C++17	65 / 100	61 ms	12336 KiB

pipes

#include <bits/stdc++.h>
using namespace std;

#define N 100000
#define M 500000

vector<pair<unsigned, unsigned>> g[N];
int64_t y[N], ans[M];

int64_t solve_for_tree(unsigned u, unsigned p1 = -1, unsigned p2 = -1)
{
    int64_t val = 0;

    for (auto const &[v, i] : g[u])
        if (v != p1 && v != p2)
        {
            int64_t z = solve_for_tree(v, u);
            ans[i] = y[v] - z;
            val += ans[i];
        }

    return val;
}

int main()
{
    size_t n, m;
    scanf("%zu %zu", &n, &m);

    if (m > n)
    {
        printf("0\n");
        return 0;
    }

    for (size_t i = 0; i < n; i++)
        scanf("%" PRId64, y + i);
    for (size_t i = 0; i < m; i++)
    {
        unsigned u, v;
        scanf("%u %u", &u, &v);
        g[u - 1].emplace_back(v - 1, i);
        g[v - 1].emplace_back(u - 1, i);
    }

    if (m + 1 == n)
        solve_for_tree(0);
    else
    {
    }

    for (size_t i = 0; i < m; i++)
        printf("%" PRId64 "\n", 2 * ans[i]);
}

Compilation message (stderr)

pipes.cpp: In function 'int main()':
pipes.cpp:28:10: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
   28 |     scanf("%zu %zu", &n, &m);
      |     ~~~~~^~~~~~~~~~~~~~~~~~~
pipes.cpp:37:14: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
   37 |         scanf("%" PRId64, y + i);
      |         ~~~~~^~~~~~~~~~~~~~~~~~~
pipes.cpp:41:14: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
   41 |         scanf("%u %u", &u, &v);
      |         ~~~~~^~~~~~~~~~~~~~~~~

• Subtask 1: 30 / 30
• Subtask 2: 35 / 70