Submission #292506

#	Time	Username	Problem	Language	Result	Execution time	Memory
292506		Aldas25	Roller Coaster Railroad (IOI16_railroad)	C++14	64 / 100	1000 ms	49752 KiB

railroad

#include "railroad.h"
#include <bits/stdc++.h>

using namespace std;

#define FOR(i, a, b) for (int i = (a); i <= (b); i++)
#define REP(n) FOR(O, 1, (n))
#define f first
#define s second
#define pb push_back
typedef vector<int> vi;
typedef long long ll;
typedef pair<int, int> pii;
typedef vector<pii> vii;

const int MAXN = 1000100;
const ll INF = 1e16;

int bitCnt (int x, int n) {
    int ret = 0;
    FOR(i, 0, n-1)
        if (x & (1<<i))
            ret ++;
    return ret;
}

ll dp[1 << 17][20];
ll solveDP (vi s, vi t, int n) {

    //FOR(i, 0, n-1) {
    //    cout << " i = " << i << "  s = " << s[i] << " t = " << t[i] << endl;
    //}

    vii srt;
    FOR(mask, 0, (1<<n)-1) {
        if (mask != 0) srt.pb({bitCnt(mask, n), mask});
        FOR(i, 0, n-1) dp[mask][i] = INF;
    }
    sort(srt.begin(), srt.end());

    //FOR(i, 0, n-1) dp[0][i] = 0;

    for (auto p : srt) {
        int mask = p.s;
        int bcnt = p.f;
        if (bcnt == 1) {
            int b = 0;
            FOR(i, 0, n-1)
                if (mask & (1<<i))
                    b = i;
            dp[mask][b] = 0ll;
        } else {
            FOR(i, 0, n-1) FOR(j, 0, n-1) {
                if (!(mask & (1<<i))) continue;
                if (!(mask & (1<<j))) continue;
                ll newVal = dp[mask ^ (1<<i)][j];
                newVal += max(0ll, (ll)t[j] - s[i]);
                dp[mask][i] = min(dp[mask][i], newVal);
            }
        }
    }

    ll ret = dp[(1<<n)-1][0];
    FOR(i, 0, n-1) ret = min (ret, dp[(1<<n)-1][i]);

    return ret;
}

int pref[MAXN];
int par[MAXN];
int balance[MAXN];
int find (int a) {return par[a] = par[a]==a ? a : find(par[a]);}
bool same (int a, int b) {return find(a) == find(b);}
void unite (int a, int b) {
    a = find(a), b = find(b);
    if (a == b) return;
    par[b] = a;
}

long long plan_roller_coaster(std::vector<int> s, std::vector<int> t) {
    int n = (int) s.size();

    if (n <= 16) return solveDP(s, t, n);

    s.pb((int)1000 * 1000 * 1000);
    t.pb(1);

    set<int> cur;
    map<int, int> toId;
    FOR(i, 0, n) cur.insert(s[i]);
    FOR(i, 0, n) cur.insert(t[i]);

    int curId = 0;
    for (int x : cur)
        toId[x] = ++curId;

    FOR(i, 0, curId+5) par[i] = i;

    FOR(i, 0, n) s[i] = toId[s[i]];
    FOR(i, 0, n) t[i] = toId[t[i]];

    //FOR(i, 0, n) cout << " i = " << i << " s[i] = " << s[i] << "  t[i] = " << t[i] << endl;

    FOR(i, 0, n) pref[s[i]]++, pref[t[i]]--;
   // FOR(i, 1, curId) cout <<"  i = "  << i<< " pref: " << pref[i] << endl;

    int ss = 0;
    FOR(i, 1, curId-1) {
        ss += pref[i];
        balance[i] = ss;
       // cout << " i = " << i << "  balance: " << balance[i] << endl;
    }

    FOR(i, 0, n) unite(s[i], t[i]);
    FOR(i, 1, curId-1) {
        if (balance[i] > 0) return 1;
        if (balance[i] < 0) unite(i, i+1);
    }

    FOR(i, 1, curId-1)
        if (!same(i, i+1))
            return 1;

    return 0;

}

• Subtask 1: 11 / 11
• Subtask 2: 23 / 23
• Subtask 3: 30 / 30
• Subtask 4: 0 / 36