Submission #1283587

#	Time	Username	Problem	Language	Result	Execution time	Memory
1283587		stanwaibbange	Roller Coaster Railroad (IOI16_railroad)	C++20	30 / 100	180 ms	12376 KiB

railroad

#include "railroad.h"
#include <bits/stdc++.h>
using namespace std;
const int INF = 1'000'000'001;

// int main() {
//     int n;
//     assert(1 == scanf("%d", &n));
//     std::vector<int> s(n), t(n);
//     for (int i = 0; i < n; ++i)
//         assert(2 == scanf("%d%d", &s[i], &t[i]));
//     long long ans = plan_roller_coaster(s, t);
//     printf("%lld\n", ans);
//     return 0;
// }

void build(int n, vector<pair<int,int>> &in, int &len, vector<int> &seg) {
    len = 2 << __lg(n);
    seg.resize(2*len,INF);
    for (int i{0};i<n;i++) {
        seg[len+i] = in[i].first;
    }
    for (int i{len-1};i>=1;i--) {
        seg[i] = min(seg[2*i],seg[2*i+1]);
    }
}

void update(int len, vector<int> &seg,int i, int v) {
    i += len;
    seg[i] = v;
    for (i/=2;i>=1;i/=2) {
        seg[i] = min(seg[2*i],seg[2*i+1]);
    }
}

int fmin(int len, vector<int> &seg) {
    int i = 1;
    while (i < len) {
        if (seg[2*i] < seg[2*i + 1]) {
            i = 2*i;
        }
        else {
            i = 2*i + 1;
        }
    }
    return i - len;
}

int search(int len, vector<int> &seg, int v) {
    int i = 1;
    while (i < len) {
        if (seg[i] <= v) {
            if (seg[2*i+1] <= v) {
                i = 2*i+1;
            }
            else {
                i = 2*i;
            }
        }
        else {
            if (seg[2*i] <= seg[2*i+1]) {
                i = 2*i;
            }
            else {
                i = 2*i+1;
            }
        }
    }
    return i - len;
}

// int search(int n, vector<pair<int,int>> &v, int w) {
//     int l = 0;
//     int r = n-1;
//     while (r >= l) {
//         int i = (l+r)/2;
//         if (v[i].first == w) {
//             return v[i].second;
//         }
//         if (v[i].first > w) {
//             r = i-1;
//         }
//         else {
//             l = i+1;
//         }
//     }
//     return v[r+1].second;
// }

long long plan_roller_coaster(std::vector<int> s, std::vector<int> t) {
    int n = (int) s.size()+1;
    s.push_back(INF);
    t.push_back(0);
    // int len1{};
    // int len2{};
    // vector<int> seg1{};
    // vector<int> seg2{};
    // build(n,s,len1,seg1);
    // build(n,t,len2,seg2);
    vector<pair<int,int>> ss(n);
    vector<pair<int,int>> tt(n);
    for (int i{0};i<n;++i) {
        ss[i] = {s[i],i};
        tt[i] = {t[i],i};
    }
    sort(ss.begin(),ss.end());   
    sort(tt.begin(),tt.end());
    vector<int> si(n);
    vector<int> ti(n);
    for (int i{0};i<n;++i) {
        si[ss[i].second] = i;
        ti[tt[i].second] = i;
    }
    int len1{};
    int len2{};
    vector<int> seg1{};
    vector<int> seg2{};
    build(n,ss,len1,seg1);
    build(n,tt,len2,seg2);
    int out = 0;

    for (int i{1};i<n;++i) {
        // cout << s[i] << " " << t[i] << "\n";
        // int a = fmin(len1,seg1);
        // update(len1,seg1,a,INF);
        // update(len2,seg2,a,INF);
        // int b = fmin(len2,seg2);
        // out += max(0,t[b]-s[a]);
        // update(len2,seg2,b,t[a]);
        // t[b] = t[a];
        // s[a] = INF;
        // t[a] = INF;
        int a = ss[search(len1,seg1,0)].second;
        update(len1,seg1,si[a],INF);
        update(len2,seg2,ti[a],INF);
        int b = tt[search(len2,seg2,s[a])].second;
        out += max(0,t[b]-s[a]);
        update(len2,seg2,ti[b],t[a]);
        t[b] = t[a];
        tt[b].first = tt[a].first;
    }

    return out;
}

Compilation message (stderr)

railroad.h:1:9: warning: #pragma once in main file
    1 | #pragma once
      |         ^~~~
railroad_c.h:1:9: warning: #pragma once in main file
    1 | #pragma once
      |         ^~~~

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