Submission #43226

#	Time	Username	Problem	Language	Result	Execution time	Memory
43226		szawinis	Wiring (IOI17_wiring)	C++14	100 / 100	155 ms	76372 KiB

wiring

#include "wiring.h"
#include <bits/stdc++.h>
#define pos first
#define col second
using namespace std;
using ll = long long;
const int N = 2e5+1;
const ll INF = 1e17;

int n;
vector<pair<int,int> > a;
ll s[N], dp[N];
inline ll fl(int j, int k) { // j, k part of sum when i-k < k-j
	return dp[j] + s[j] - 2*s[k] - 1ll * (j-2*k) * a[k+1].pos;
}
inline ll fg(int j, int k) {
	return dp[j] + s[j] - 2*s[k] - 1ll * (j-2*k) * a[k].pos;
}
set<pair<ll,int> > stl, stg; // l: j <= 2*k-i, g: j > 2*k-i
ll min_total_length(std::vector<int> r, std::vector<int> b) {
	n = r.size() + b.size();
	for(int i = 0; i < r.size(); i++) a.emplace_back(r[i], 0);
	for(int i = 0; i < b.size(); i++) a.emplace_back(b[i], 1);
	a.emplace_back(INT_MIN, INT_MIN);
	sort(a.begin(), a.end());
	for(int i = 1; i <= n; i++) s[i] = s[i-1] + a[i].pos;
	fill(dp+1, dp+n+1, INF);
	for(int i = 2, k = 0; i <= n; i++) {
		if(a[i].col != a[i-1].col) {
			k = i-1;
			stl.clear();
			stg.clear();
			for(int j = k-1; j >= 0 && a[j+1].col == a[k].col; j--)
				stl.emplace(fl(j, k), j);
		}
		if(!k) continue;
		// case segments completely disjoint
		if(!stl.empty()) dp[i] = min(stl.begin()->first + s[i] - 1ll * i * a[k+1].pos, dp[i]);
		if(!stg.empty()) dp[i] = min(stg.begin()->first + s[i] - 1ll * i * a[k].pos, dp[i]);
		if(!stl.empty()) {
			stl.erase(make_pair(fl(2*k-i, k), 2*k-i));
			stg.emplace(make_pair(fg(2*k-i, k), 2*k-i));
		}
		// special case: segments intersect at one node
		if(k-1 >= 1 && a[k-1].col == a[i].col)
			dp[i] = min(dp[k] + s[i] - s[k] - 1ll * (i-k) * a[k].pos, dp[i]);
	}
	return dp[n];
}

Compilation message (stderr)

wiring.cpp: In function 'll min_total_length(std::vector<int>, std::vector<int>)':
wiring.cpp:22:19: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
  for(int i = 0; i < r.size(); i++) a.emplace_back(r[i], 0);
                   ^
wiring.cpp:23:19: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
  for(int i = 0; i < b.size(); i++) a.emplace_back(b[i], 1);
                   ^

• Subtask 1: 7 / 7
• Subtask 2: 13 / 13
• Subtask 3: 10 / 10
• Subtask 4: 25 / 25
• Subtask 5: 45 / 45