oj.uz

Submission #834231

# Submission time Handle Problem Language Result Execution time Memory
834231 2023-08-22T12:05:18 Z Josia Ancient Books (IOI17_books) C++17
0 / 100
 1 ms 596 KB 
#include "books.h"
#include <bits/stdc++.h>

using namespace std;

#define int int64_t


vector<int> p;
int s;
int n;
int ret;

struct cycle {
	int left=1e9, right=-1e9;
	set<int> points;
};
bool CycleLess(cycle &a, cycle &b) {
	return pair<int, int>{a.left, a.right} < pair<int, int>{b.left, b.right};
}
bool merge(cycle &a, cycle &b) {			// a<-b
	if (!(a.left < b.left && a.right < b.right && a.right > b.left)) return 0;

	if (a.points.size() < b.points.size()) swap(a, b);

	a.right = b.right;
	for (int i: b.points) a.points.insert(i);
	
	return 1;
}
bool contains(cycle &a, cycle &b) {
	return (a.left <= b.left && b.right <= a.right);
}



vector<bool> vis;
cycle getCycle(int v) {
	// assert(vis[v]==0);

	cycle res;

	while (vis[v] == 0) {
		vis[v] = 1;
		res.left = min(res.left, v);
		res.right = max(res.right, v);
		res.points.insert(v);

		ret += abs(v-p[v]);
		v = p[v];
	}
	return res;
}

vector<cycle> mergedCycles;
vector<int> parents;

int dfs(int v, int par) {
	parents[v] = par;
	int w = v+1;

	while (w<(int)mergedCycles.size() && contains(mergedCycles[v], mergedCycles[w])) {
		w = dfs(w, v);
	}
	return w;
}


void solve() {
	vis.assign(n, 0);

	vector<cycle> cycles;

	if (p[s]==s) cycles.push_back({s, s, {s}});
	int globLeft=s, globRight=s;

	for (int i = 0; i<n; i++) {
		if (vis[i]) continue;
		cycles.push_back(getCycle(i));
		if (cycles.back().left == cycles.back().right) cycles.pop_back();
		else {
			globLeft = min(globLeft, cycles.back().left);
			globRight = max(globRight, cycles.back().right);
		}
	}

	sort(cycles.begin(), cycles.end(), CycleLess);

	vector<int> inds;

	priority_queue<pair<int, int>> pq;

	for (int i = 0; i<(int)(cycles.size()); i++) {
		while (pq.size() && merge(cycles[i], cycles[pq.top().second])) {
			pq.pop();
		}
		// if(merge(cycles[i+1], cycles[i])) continue;

		pq.push({cycles[i].right, i});

		// inds.push_back(i);
	}
	while (pq.size()) {
		inds.push_back(pq.top().second);
		pq.pop();
	}
	reverse(inds.begin(), inds.end());

	mergedCycles.clear();
	for (int i: inds) mergedCycles.push_back(cycles[i]);


	for (int i = 0; i<mergedCycles.size(); i++) {
		for (int j = 0; j<mergedCycles.size(); j++) {
			auto a = mergedCycles[i];
			auto b = mergedCycles[j];
			assert(!(a.left < b.left && a.right < b.right && a.right > b.left));
		}
	}


	parents.assign(mergedCycles.size(), -1);
	for (int i = 0; i<(int)mergedCycles.size(); i=dfs(i, -1));


	int pos=-1;
	for (int i = 0; i<(int)mergedCycles.size(); i++) {
		if (mergedCycles[i].points.count(s)) pos = i;
	}
	// assert(pos!=-1);



	vector<pair<int, int>> jump(n);

	for (int i = 0; i<n; i++) {
		jump[i]={i, i};
	}

	for (int i: inds) {
		for (int j: cycles[i].points) {
			jump[j].first = cycles[i].left;
			jump[j].second = cycles[i].right;
		}
	}
	// return;

	// for(int i: parents) cerr << i << " ";
	// cerr << "\n";

	
	while (parents[pos] != -1) {
		cycle elem = mergedCycles[pos];
		cycle parent = mergedCycles[parents[pos]];

		auto goRightPoint = parent.points.lower_bound(elem.left);
		auto goLeftPoint = prev(parent.points.upper_bound(elem.right));

		// assert(parent.points.lower_bound(elem.left) != parent.points.end());
		// assert(parent.points.upper_bound(elem.right) != parent.points.begin());

		// let's hope it'll not go wrong.

		int right = *goRightPoint, left = *goLeftPoint;

		// if (right <= elem.right || left >= elem.left) {
		// 	pos = parents[pos];
		// 	continue;
		// }

		int costRight = 0;
		int posToRight = elem.right;
		while (posToRight < right) {
			costRight++;
			posToRight = jump[posToRight+1].second;
		}

		int costLeft = 0;
		int posToLeft = elem.left;
		while (posToLeft > left) {
			costLeft++;
			posToLeft = jump[posToLeft-1].first;
		}

		ret += 2*min(costLeft, costRight);

		pos = parents[pos];
	}

	vector<int> noParent;

	for (int i = 0; i<(int)parents.size(); i++) {
		if (parents[i] == -1) noParent.push_back(i);
	}

	for (int i = 0; i<(int)(noParent.size())-1; i++) {
		// assert(mergedCycles[i+1].left>mergedCycles[i].right);
		ret+=2*(mergedCycles[i+1].left-mergedCycles[i].right);
	}
}


long long minimum_walk(vector<signed> _p, signed _s) {
	ret = 0;
	s = _s;
	n = _p.size();
	p.resize(n); for (int i = 0; i<n; i++) p[i] = _p[i];

	
	solve();


	return ret;
}

Compilation message

books.cpp: In function 'void solve()':
books.cpp:113:19: warning: comparison of integer expressions of different signedness: 'int64_t' {aka 'long int'} and 'std::vector<cycle>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
  113 |  for (int i = 0; i<mergedCycles.size(); i++) {
      |                  ~^~~~~~~~~~~~~~~~~~~~
books.cpp:114:20: warning: comparison of integer expressions of different signedness: 'int64_t' {aka 'long int'} and 'std::vector<cycle>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
  114 |   for (int j = 0; j<mergedCycles.size(); j++) {
      |                   ~^~~~~~~~~~~~~~~~~~~~

Subtask #1
0 / 12.0

# Verdict Execution time Memory Grader output
1 Correct 1 ms 212 KB Output is correct
2 Correct 1 ms 212 KB Output is correct
3 Correct 1 ms 212 KB Output is correct
4 Correct 1 ms 212 KB Output is correct
5 Correct 1 ms 212 KB Output is correct
6 Incorrect 1 ms 212 KB 3rd lines differ - on the 1st token, expected: '8', found: '4'
7 Halted 0 ms 0 KB -

Subtask #2
0 / 10.0

# Verdict Execution time Memory Grader output
1 Correct 1 ms 212 KB Output is correct
2 Correct 1 ms 212 KB Output is correct
3 Correct 1 ms 212 KB Output is correct
4 Correct 1 ms 212 KB Output is correct
5 Correct 1 ms 212 KB Output is correct
6 Incorrect 1 ms 212 KB 3rd lines differ - on the 1st token, expected: '8', found: '4'
7 Halted 0 ms 0 KB -

Subtask #3
0 / 28.0

# Verdict Execution time Memory Grader output
1 Correct 1 ms 212 KB Output is correct
2 Correct 1 ms 212 KB Output is correct
3 Correct 1 ms 212 KB Output is correct
4 Correct 1 ms 212 KB Output is correct
5 Correct 1 ms 212 KB Output is correct
6 Incorrect 1 ms 212 KB 3rd lines differ - on the 1st token, expected: '8', found: '4'
7 Halted 0 ms 0 KB -

Subtask #4
0 / 20.0

# Verdict Execution time Memory Grader output
1 Runtime error 1 ms 596 KB Execution killed with signal 6
2 Halted 0 ms 0 KB -

Subtask #5
0 / 30.0

# Verdict Execution time Memory Grader output
1 Correct 1 ms 212 KB Output is correct
2 Correct 1 ms 212 KB Output is correct
3 Correct 1 ms 212 KB Output is correct
4 Correct 1 ms 212 KB Output is correct
5 Correct 1 ms 212 KB Output is correct
6 Incorrect 1 ms 212 KB 3rd lines differ - on the 1st token, expected: '8', found: '4'
7 Halted 0 ms 0 KB -