Submission #47301

#	Time	Username	Problem	Language	Result	Execution time	Memory
47301		TAMREF	Roller Coaster Railroad (IOI16_railroad)	C++11	64 / 100	385 ms	115364 KiB

railroad

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

typedef long long ll;
const int mx = 4e5 + 5;

ll dp[16][1<<16];
vector<int> X;
vector<int> O[mx];
int deg[mx];
bool vis[mx];

void dfs(int x){
    vis[x] = 1;
    for(int &u : O[x]){
        if(!vis[u]) dfs(u);
    }
}

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

    if(n > 16)
    {
        for(int i = 0; i < n; i++){
            X.push_back(s[i]);
            X.push_back(t[i]);
        }
        sort(X.begin(),X.end());
        X.erase(unique(X.begin(),X.end()),X.end());
        for(int i = 0; i < n; i++){
            s[i] = lower_bound(X.begin(),X.end(),s[i]) - X.begin();
            t[i] = lower_bound(X.begin(),X.end(),t[i]) - X.begin();
            ++deg[ s[i] ];
            --deg[ t[i] ];
            O[ s[i] ].push_back(t[i]);
        }
        for(int i = 0; i < X.size(); i++){
            int cnt = (i == 0) - deg[i];
            if(cnt > 0){
                deg[i] += cnt;
                deg[i+1] -= cnt;
                O[i].push_back(i+1);
            }else if(cnt < 0) return 42;
        }
        dfs(0);
        for(int i = 0; i < X.size(); i++) if(!vis[i]) return 42;
        return 0;
    }
    for(int i = 0; i < n; i++) fill(dp[i], dp[i] + (1 << n), LLONG_MAX);
    for(int i = 0; i < n; i++) dp[i][1<<i] = 0;

    for(int b = 1; b < (1 << n); b++){
        for(int i = 0; i < n; i++){
            if(!(b >> i & 1)) continue;
            for(int j = 0; j < n; j++){
                if(b >> j & 1) continue;
                ll &d = dp[j][b | (1 << j)];
                d = min(d, dp[i][b] + max(0, t[i]-s[j]));
            }
        }
    }
    ll ans = LLONG_MAX;
    for(int i = 0; i < n; i++){
        ans = min(ans, dp[i][(1<<n)-1]);
    }
    return ans;
}

Compilation message (stderr)

railroad.cpp: In function 'll plan_roller_coaster(std::vector<int>, std::vector<int>)':
railroad.cpp:39:26: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
         for(int i = 0; i < X.size(); i++){
                        ~~^~~~~~~~~~
railroad.cpp:48:26: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
         for(int i = 0; i < X.size(); i++) if(!vis[i]) return 42;
                        ~~^~~~~~~~~~

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