Submission #99985

#	Time	Username	Problem	Language	Result	Execution time	Memory
99985		dwsc	Roller Coaster Railroad (IOI16_railroad)	C++14	34 / 100	179 ms	16180 KiB

railroad

#include "railroad.h"
#include <bits/stdc++.h>
using namespace std;
typedef pair<int,int> ii;
long long memo[20][100000];
int n;
int arr1[20],arr2[20];
long long dp(int prev,int bm){
    if (bm == (1<<n)-1) return 0;
    if (memo[prev][bm] != -1) return memo[prev][bm];
    memo[prev][bm] = 1e18;
    for (int i = 0; i < n; i++){
        if (bm & (1<<i)) continue;
        int cost = max(0,arr2[prev]-arr1[i]);
        memo[prev][bm] = min(memo[prev][bm],dp(i,bm+(1<<i))+cost);
    }
    return memo[prev][bm];
}
long long plan_roller_coaster(std::vector<int> s, std::vector<int> t) {
    n = (int) s.size();
    if (n > 20){
        vector<ii> up,down;
        for (int i = 0; i < n; i++){
            if (s[i] <= t[i]) up.push_back(ii(s[i],t[i]));
            else down.push_back(ii(s[i],t[i]));
        }
        sort(up.begin(),up.end());
        sort(down.begin(),down.end());
        int p1 = 0,p2 = 0;
        int pos = 0;
        long long ans = 0;
        while (p1 != up.size() && p2 != down.size()){
            if (p1 == up.size()){
                int s = down[p2].first, t = down[p2].second;
                ans += max(pos-s,0);
                pos = t;
                p2++;
            }
            else if (p2 == up.size()){
                int s = up[p1].first, t = up[p2].second;
                ans += max(pos-s,0);
                pos = t;
                p1++;
            }
            else{
                int s1 = down[p2].first, t1 = down[p2].second;
                int s2 = up[p1].first, t2 = up[p2].second;
                if (t2 > s1){
                     ans += max(pos-s1,0);
                     pos = t1;
                     p2++;
                }
                else{
                    ans += max(pos-s2,0);
                    pos = t2;
                    p1++;
                }
            }
        }
        return ans;
    }
    for (int i = 0; i < n; i++){
        arr1[i] = s[i];
        arr2[i] = t[i];
    }
    for (int i = 0; i < 20; i++)for (int j = 0; j < 100000; j++) memo[i][j] = -1;
    long long ans = 1e18;
    for (int i = 0; i < n; i++) ans = min(ans,dp(i,1<<i));
    return ans;
}

Compilation message (stderr)

railroad.cpp: In function 'long long int plan_roller_coaster(std::vector<int>, std::vector<int>)':
railroad.cpp:32:19: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
         while (p1 != up.size() && p2 != down.size()){
                ~~~^~~~~~~~~~~~
railroad.cpp:32:38: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
         while (p1 != up.size() && p2 != down.size()){
                                   ~~~^~~~~~~~~~~~~~
railroad.cpp:33:20: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
             if (p1 == up.size()){
                 ~~~^~~~~~~~~~~~
railroad.cpp:39:25: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
             else if (p2 == up.size()){
                      ~~~^~~~~~~~~~~~

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