Submission #578355

#	Time	Username	Problem	Language	Result	Execution time	Memory
578355		SlavicG	Stations (IOI20_stations)	C++17	52.32 / 100	1460 ms	804 KiB

stations

#include "stations.h"
#include "bits/stdc++.h"
using namespace std;

const int N = 1000;
vector<int> adj[N];
int in[N], sz[N], tt = 0;
void dfs(int u, int par) {
    in[u] = tt++;
    sz[u] = 1;
    for(int v: adj[u]) {
        if(v == par) continue;
        dfs(v, u);
        sz[u] += sz[v];
    }
}
std::vector<int> label(int n, int k, std::vector<int> u, std::vector<int> v) {
	std::vector<int> labels(n);
	for(int i = 0; i < n; ++i) {
        adj[i].clear();
        tt = 0;
        sz[i] = 0, in[i] = 0;
	}
	for(int i = 0; i < n - 1; ++i) {
        adj[u[i]].push_back(v[i]);
        adj[v[i]].push_back(u[i]);
	}
	dfs(0, -1);
	if(k <= 1000) {
        iota(labels.begin(), labels.end(), 0);
        return labels;
	}
	for (int i = 0; i < n; i++) {
		labels[i] = 1000 * sz[i] + in[i];
	}
	return labels;
}

int find_next_station(int s, int t, std::vector<int> c) {
    if(s <= 1000 && t <= 1000) {
        for(int i = 0; i < 1000; ++i) {
            adj[i].clear();
            tt = 0;
            in[i] = sz[i] = 0;
        }
        for(int i = 0; i < 999; ++i) {
            adj[i + 1].push_back(i / 2);
            adj[i / 2].push_back(i + 1);
        }
        dfs(0, -1);
        if(in[s] <= in[t] && in[t] <= in[s] + sz[s] - 1) {
            for(auto x: c) {
                if(in[x] <= in[t] && in[t] <= in[x] + sz[x] - 1) return x;
            }
        } else {
            int mn = INT_MAX, idx = -1;
            for(auto x: c) {
                int val = in[x];
                if(val < mn) {
                    mn = val;
                    idx = x;
                }
            }
            assert(idx != -1);
            return idx;
        }

    }

    int in_s = s % 1000, in_t = t % 1000, sz_s = s / 1000, sz_t = t / 1000;
    if(in_s <= in_t && in_t <= in_s + sz_s - 1) {
        for(auto x: c) {
            int in_c = x % 1000, sz_c = x / 1000;
            if(in_c <= in_t && in_t <= in_c + sz_c - 1) return x;
        }
    } else {
        int mn = INT_MAX, idx = -1;
        for(auto x: c) {
            int val = x % 1000;
            if(val < mn) {
                mn = val;
                idx = x;
            }
        }
        assert(idx != -1);
        return idx;
    }
}

Compilation message (stderr)

stations.cpp: In function 'int find_next_station(int, int, std::vector<int>)':
stations.cpp:70:60: warning: unused variable 'sz_t' [-Wunused-variable]
   70 |     int in_s = s % 1000, in_t = t % 1000, sz_s = s / 1000, sz_t = t / 1000;
      |                                                            ^~~~
stations.cpp:88:1: warning: control reaches end of non-void function [-Wreturn-type]
   88 | }
      | ^

• Subtask 1: 0 / 5
• Subtask 2: 0 / 8
• Subtask 3: 16 / 16
• Subtask 4: 10 / 10
• Subtask 5: 26.3205 / 61