Submission #98463

#	Time	Username	Problem	Language	Result	Execution time	Memory
98463		bogdan10bos	Ancient Books (IOI17_books)	C++14	12 / 100	3 ms	512 KiB

books

#include <bits/stdc++.h>
#include "books.h"

using namespace std;

typedef long long LL;
typedef pair<int, int> pii;
typedef pair<int, pii> p3i;

LL minimum_walk(vector<int> p, int s)
{
	LL ans = 0LL;
	int N = p.size();
	for(int i = 0; i < N; i++)
        ans += abs(i - p[i]);

    vector<int> f;
    f.resize(N);
    for(int i = 0; i < N; i++)  f[i] = i;
    function<int(int)> F = [&](int x) -> int { if(x == f[x]) return x; return f[x] = F(f[x]); } ;

    for(int i = 0; i < N; i++)
    {
        int fx = F(i), fy = F(p[i]);
        if(fx == fy)    continue;
        f[fy] = fx;
    }

    vector<int> nodes;
    vector<p3i> edges;
    for(int i = 0; i < N; i++)
        if(p[i] != i)
            nodes.push_back(i);
    for(int i = 0; i < nodes.size(); i++)
    {
        int nod = nodes[i];
        edges.push_back({abs(s - nod), {s, nod}});
        if(i > 0)
        {
            int lst = nodes[i - 1];
            edges.push_back({abs(nod - lst) + abs(lst - p[nod]) - abs(nod - p[nod]), {nod, lst}});
        }
    }

    sort(begin(edges), end(edges));

    for(auto &e: edges)
    {
        int cst = e.first, x = e.second.first, y = e.second.second;

        int fx = F(x), fy = F(y);
        if(fx == fy)    continue;

        ans += 2LL * cst;
        f[fy] = fx;
    }

    return ans;
}

Compilation message (stderr)

books.cpp: In function 'LL minimum_walk(std::vector<int>, int)':
books.cpp:34:22: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
     for(int i = 0; i < nodes.size(); i++)
                    ~~^~~~~~~~~~~~~~

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