Submission #100108

#	Time	Username	Problem	Language	Result	Execution time	Memory
100108		owl10124	Roller Coaster Railroad (IOI16_railroad)	C++14	34 / 100	249 ms	23888 KiB

railroad

#include <bits/stdc++.h>
//#include "railroad.h"
using namespace std;
typedef long long ll;
typedef pair<int,int> ii;

struct seg {
    int b,m,e;
    ii v;
    seg *l,*r;
    seg(int nl, int nr) {
        b=nl,e=nr,m=(nl+nr)/2,v=make_pair(0,0);
        if (b!=e) l=new seg(b,m), r=new seg(m+1,e);
    }
    void upd(int p, int nv) {
        if (b==e) {
            v=max(v,make_pair(nv,b)); return;
        }
        if (p<=m) l->upd(p,nv);
        else r->upd(p,nv);
        v=max(l->v,r->v);
    }
    ii rmax(int nl, int nr) {
        if (nl>nr) return make_pair(-1,0);
        if (nl<=b&&e<=nr) return v;
        ii val = make_pair(0,0);
        if (nl<=m) val=max(val,l->rmax(nl,nr));
        if (m<nr) val=max(val,r->rmax(nl,nr));
        return val;
    }
};

vector<ii> segs;

int n;

ll m[16][65536];

ll dp(int seg, int bm) {
    if (bm==(1<<n)-1) return m[seg][bm]=0;
    if (seg!=-1&&m[seg][bm]!=-1) return m[seg][bm];
    ll l = 1ll<<60;
    for (int i=0;i<n;i++) {
        if (((1<<i)&~bm)) l=min(l,(seg!=-1&&segs[seg].second>segs[i].first?segs[seg].second-segs[i].first:0)+dp(i,bm|(1<<i)));
    }
    //printf("%d %d %d %lld\n",segs[seg].second,seg,bm,l);
    return (seg!=-1 ? m[seg][bm]=l : l);
}

ll plan_roller_coaster(std::vector<int> s, std::vector<int> t) {
    n = (int) s.size();
    for (int i=0;i<n;i++) segs.push_back(make_pair(s[i],t[i]));
    if (n<=16) {
        fill(&m[0][0],&m[16][0],-1);
        return dp(-1,0);
    } else {
        //sort by enter speed? then get lowest exit...
        seg s(0,n-1);
        sort(segs.begin(),segs.end());
        for (int i=0;i<n;i++) s.upd(i,segs[i].second);
        int rem=n, speed=0;

        ii buf = s.rmax(0,n-1);
        s.upd(buf.second,0);

        while (rem--) {
            buf = s.rmax(lower_bound(segs.begin(),segs.end(),make_pair(speed,0))-segs.begin(),n-1);
            //printf("%d %d ",buf.first,buf.second);
            speed=buf.first;
            if (speed==-1) return 0;
            s.upd(buf.second,-1);
            //printf("%d %d\n",lower_bound(segs.begin(),segs.end(),make_pair(speed,0))-segs.begin(),speed);
        }
        return 1;
    }
}

Compilation message (stderr)

railroad.cpp: In function 'll plan_roller_coaster(std::vector<int>, std::vector<int>)':
railroad.cpp:40:35: warning: array subscript is below array bounds [-Warray-bounds]
     if (bm==(1<<n)-1) return m[seg][bm]=0;
                              ~~~~~^

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