Submission #137294

#	Time	Username	Problem	Language	Result	Execution time	Memory
137294		choikiwon	Ancient Books (IOI17_books)	C++17	50 / 100	223 ms	20584 KiB

books

#include "books.h"
#include<bits/stdc++.h>
using namespace std;

typedef long long ll;
typedef pair<int, int> pii;

const int maxn = 1000010;

int N, S;
int A[maxn], vis[maxn];
vector<pii> V;

ll minimum_walk(std::vector<int> p, int s) {
	N = p.size();
	S = s;
	for(int i = 0; i < N; i++) {
        A[i] = p[i];
	}

	ll ret = 0;
	for(int i = 0; i < N; i++) {
        if(vis[i]) continue;
        if(A[i] == i) continue;

        int mx = -1e9;

        int u = i;
        while(!vis[u]) {
            vis[u] = 1;
            mx = max(mx, u);

            ret += abs(u - A[u]);
            u = A[u];
        }

        V.push_back(pii(i, mx));
	}

	if(V.size() == 0) return ret;

	int st = V[0].first;
	int ed = V[0].second;

	for(int i = 1; i < V.size(); i++) {
        if(ed < V[i].first) {
            ret += 2 * (V[i].first - ed);

            st = V[i].first;
            ed = V[i].second;
            continue;
        }
        ed = max(ed, V[i].second);
	}

	int mn = 1e9;
	for(int i = 0; i < N; i++) if(vis[i]) mn = min(mn, abs(i - S));
	ret += 2 * mn;

	return ret;
}

Compilation message (stderr)

books.cpp: In function 'll minimum_walk(std::vector<int>, int)':
books.cpp:45:19: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
  for(int i = 1; i < V.size(); i++) {
                 ~~^~~~~~~~~~
books.cpp:42:6: warning: variable 'st' set but not used [-Wunused-but-set-variable]
  int st = V[0].first;
      ^~

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