Submission #1060848

#	Time	Username	Problem	Language	Result	Execution time	Memory
1060848		onbert	Ancient Books (IOI17_books)	C++17	0 / 100	1 ms	348 KiB

books

#include "books.h"
#include <bits/stdc++.h>
using namespace std;
#define int long long
const int INF = 1e9;

int minimum_walk(vector<int32_t> p, int32_t s) {
    int n = p.size();
    bool vis[n];
    for (int i=0;i<n;i++) vis[i] = false;
    int ans = 0;
    vector<pair<int,int>> vec;
    int L = s, R = s;
    for (int i=0;i<n;i++) if (!vis[i]) {
        if (p[i]==i) continue;
        int u = i;
        pair<int,int> val = {-INF, INF};
        while (true) {
            vis[u] = true;
            if (u >= s) val.second = min(u, val.second);
            if (u <= s) val.first = max(u, val.first);
            int v = p[u];
            ans += abs(v-u);
            if (v==i) break;
            u = v;
        }
        // cout << val.first << " " << val.second << endl;
        if (val.first==-INF) R = max(val.second, R);
        else if (val.second == INF) L = min(val.first, L);
        else vec.push_back(val);
    }
    if (vec.size()==0) return ans + (R - L)*2;
    sort(vec.begin(), vec.end());
    int sz = vec.size(), l, r = s;
    int ans2 = INF;
    for (auto [x, y]:vec) {
        l = x;
        ans2 = min(max(r, R) - min(l, L), ans2);
        // cout << l << " " << r << endl;
        r = max(y, r);
    }
    ans2 = min(max(r, R) - min((int)s, L), ans2);
    return ans + ans2*2;
}

Compilation message (stderr)

books.cpp: In function 'long long int minimum_walk(std::vector<int>, int32_t)':
books.cpp:34:9: warning: unused variable 'sz' [-Wunused-variable]
   34 |     int sz = vec.size(), l, r = s;
      |         ^~

• Subtask 1: 0 / 12
• Subtask 2: 0 / 10
• Subtask 3: 0 / 28
• Subtask 4: 0 / 20
• Subtask 5: 0 / 30