| # | Time | Username | Problem | Language | Result | Execution time | Memory |
|---|---|---|---|---|---|---|---|
| 1001678 | Nomio | Race (IOI11_race) | C++17 | 0 ms | 0 KiB |
This submission is migrated from previous version of oj.uz, which used different machine for grading. This submission may have different result if resubmitted.
#include <bits/stdc++.h>
using namespace std;
int k, mn = INT_MAX;
vector<vector<int>> dp(200001, vector<int>(101, INT_MAX)); // sum I and ends at node v is the minimum of the paths
vector<pair<int, int>> adj[200001]; // save edges
vector<vector<pair<int, int>>> path; // keep the best paths of each weights
void dfs(int v, int p)
{
dp[v][0] = 0;
for (auto [i, w] : adj[v])
if (i != p)
dfs(i, v);
path.assign(k + 1, {});
for (auto [i, w] : adj[v])
{
if (i == p)
continue;
for (int j = w; j <= k; j++)
{
if (dp[i][j - w] == INT_MAX)
continue;
if (path[j].size() < 2)
path[j].push_back({dp[i][j - w] + 1, i}); // keep best two paths
else if (dp[i][j - w] + 1 < path[j][1].first)
path[j][1] = {dp[i][j - w] + 1, i}; // keep current path
if (path[j].size() == 2 && path[j][0].first > path[j][1].first)
swap(path[j][0], path[j][1]); // swap shortest path
dp[v][j] = min(dp[v][j], dp[i][j - w] + 1);
}
}
if (!path[k].empty())
mn = min(mn, path[k][0].first); // if there is any path which is exactly K
for (int i = 1; i < k; i++)
{
if (path[i].empty() || path[k - i].empty())
continue;
if (path[i][0].second != path[k - i][0].second)
mn = min(mn, path[i][0].first + path[k - i][0].first); // compare 2 best paths
else if (1 < path[k - i].size())
mn = min(mn, path[i][0].first + path[k - i][1].first); // compare 2 best paths if there is path over 1.
}
}
int best_path(int N, int K, int H[][2], int L[])
{
k = K;
for (int i = 0; i < N - 1; i++)
{
adj[H[i][0]].push_back({H[i][1], L[i]});
adj[H[i][1]].push_back({H[i][0], L[i]});
}
dfs(0, -1);
if (mn == INT_MAX)
return -1;
else
return mn;
}
#define MAX_N 500000
static int N, K;
static int H[MAX_N][2];
static int L[MAX_N];
static int solution;
inline void my_assert(int e)
{
if (!e)
abort();
}
void read_input()
{
int i;
my_assert(2 == scanf("%d %d", &N, &K));
for (i = 0; i < N - 1; i++)
my_assert(3 == scanf("%d %d %d", &H[i][0], &H[i][1], &L[i]));
my_assert(1 == scanf("%d", &solution));
}
//int main()
//{
// int ans;
// read_input();
// ans = best_path(N, K, H, L);
// if (ans == solution)
// printf("Correct.\n");
// else
// printf("Incorrect. Returned %d, Expected %d.\n", ans, solution);
//
// return 0;
//}