Submission #471135

#	Time	Username	Problem	Language	Result	Execution time	Memory
471135		jalsol	Race (IOI11_race)	C++17	21 / 100	3036 ms	11972 KiB

race

// looking to shine brighter in this world...

#define TASK "race"
#include "race.h"

#ifdef LOCAL
#include "local.h"
#else
#include <bits/stdc++.h>
#define debug(...)
#define DB(...)
#endif

using namespace std;

using ll = long long;
using ld = long double;

#define all(x) x.begin(), x.end()
#define rall(x) x.rbegin(), x.rend()
#define fi first
#define se second

#define For(i, l, r) for (int i = (l); i <= (r); ++i)
#define Ford(i, r, l) for (int i = (r); i >= (l); --i)
#define Rep(i, n) For (i, 0, (n) - 1)
#define Repd(i, n) Ford (i, (n) - 1, 0)
#define Fe(...) for (auto __VA_ARGS__)

template <class C> inline int isz(const C& c) { return static_cast<int>(c.size()); }
template <class T> inline bool chmin(T& a, const T& b) { return (a > b) ? a = b, true : false; }
template <class T> inline bool chmax(T& a, const T& b) { return (a < b) ? a = b, true : false; }

const bool __initialization = []() {
    cin.tie(nullptr)->sync_with_stdio(false);
    if (fopen(TASK".inp", "r")) {
        (void)(!freopen(TASK".inp", "r", stdin));
        (void)(!freopen(TASK".out", "w", stdout)); }
    cout << setprecision(12) << fixed;
    return true;
}();

constexpr ld eps = 1e-9;
constexpr int inf = 1e9;
constexpr ll linf = 1e18;

// ================================================================================

constexpr int maxn = 2e5 + 5;

struct Info { int v, c; };
struct State { int u, i; };

vector<Info> g[maxn];

ll d[maxn];
queue<State> q;

int Bfs(int src, int n, int k) {
    memset(d, -1, sizeof(d[0]) * n); d[src] = 0;
    q.push({ src, 0 });
    int ret = inf;

    while (isz(q)) {
        State s = q.front(); q.pop();

        if (d[s.u] > k) {
            continue;
        }
        else if (d[s.u] == k) {
            chmin(ret, s.i);
            continue;
        }

        Fe (&[v, c] : g[s.u]) {
            if (d[v] != -1) continue;
            if (d[s.u] + c > k) continue;

            d[v] = d[s.u] + c;
            q.push({ v, s.i + 1 });
        }
    }

    return ret;
}

int best_path(int n, int k, int h[][2], int l[]) {
    Rep (i, n - 1) {
        int u = h[i][0];
        int v = h[i][1];
        int c = l[i];

        g[u].push_back({ v, c });
        g[v].push_back({ u, c });
    }

    int ans = inf;

    Rep (u, n) {
        chmin(ans, Bfs(u, n, k));
    }

    if (ans == inf) ans = -1;

    return ans;
}

• Subtask 1: 9 / 9
• Subtask 2: 12 / 12
• Subtask 3: 0 / 22
• Subtask 4: 0 / 57