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Submission #331053

# Submission time Handle Problem Language Result Execution time Memory
331053 2020-11-27T06:28:30 Z ChrisGe123 Palembang Bridges (APIO15_bridge) C++14
100 / 100
 656 ms 15596 KB 
#include "bits/stdc++.h"
using namespace std;
typedef long long ll;
#include <ext/pb_ds/tree_policy.hpp>
#include <ext/pb_ds/assoc_container.hpp>
using namespace __gnu_pbds;
template <class T> using Tree = tree<T, null_type, less<T>,
    rb_tree_tag, tree_order_statistics_node_update>;

//g++ -std=c++17 -O2 -fsanitize=undefined /usr/local/Cellar/gcc/10.2.0/include/c++/10.2.0/x86_64-apple-darwin19/bits/stdc++.h
#define maxn 100005
#define mod 1000000007
int n, k;
pair<ll, pair<ll, ll> > interval[maxn]; 
ll ans;


Tree<pair<ll, int> > lendpoints;
Tree<pair<ll, int> > rendpoints;

void setupIO(string s)
{
	ios_base::sync_with_stdio(false);
	cin.tie(0);
	freopen((s + ".in").c_str(), "r", stdin);
	freopen((s + ".out").c_str(), "w", stdout);
}

ll f(int i, ll bridge)
{
	ll l = interval[i].second.first; ll r = interval[i].second.second;
	if (l <= bridge && bridge <= r)
	{
		return 0;
	}
	else if (bridge < l)
	{
		return 2 * (l-bridge);
	}
	else
	{
		return 2 * (bridge-r);
	}
}
int main()
{
	//setupIO("bridges");
	ios_base::sync_with_stdio(false);
	cin.tie(0);
	cin >> k >> n;
	int counter = 0;
	ll pre = 0;
	lendpoints.clear();
	rendpoints.clear();
	for (int i=0; i<n; i++)
	{
		char p, q;
		ll s, t;
		cin >> p >> s >> q >> t;
		if (p == q)
		{
			pre += abs(s - t);
		}
		else
		{
			ll l = min(s, t);
			ll r = max(s, t);
			interval[counter++] = make_pair(s+t, make_pair(l, r));
			pre += r - l + 1;
		}
	}
	//use the below version to make it easier to randomly generate test cases 
	// for (int i=0; i<n; i++)
	// {
	// 	ll s, t;
	// 	cin >> s >> t;
	// 	ll l = min(s, t);
	// 	ll r = max(s, t);
	// 	interval[counter++] = make_pair(s+t, make_pair(l, r));
	// 	pre += r - l + 1;
	// }
	n = counter;
	ans = 0;
	//we just want to find the median of the endpoints 
	sort(interval, interval+n);
	for (int i=0; i<n; i++)
	{
		rendpoints.insert(make_pair(interval[i].second.first, 2*i));
		rendpoints.insert(make_pair(interval[i].second.second, 2*i+1));
	}
	ll xone = rendpoints.find_by_order(n-1)->first;
	//cerr << x << endl;
	for (int i=0; i<n; i++)
	{
		ans += f(i, xone);
	}
	if (k == 2)
	{
		 //sorted in order of increasing midpoint
		// cerr << ans << endl;
		// cerr << endl;
		// cerr << endl;
		ll temp = ans;
		for (int i=0; i<n-1; i++)
		{
			//things 0 to i take the first bridge, i+1 to n-1 take the second bridge
			lendpoints.insert(make_pair(interval[i].second.first, 2*i));
			lendpoints.insert(make_pair(interval[i].second.second, 2*i+1));
			ll x = lendpoints.find_by_order(i)->first;

			rendpoints.erase(make_pair(interval[i].second.first, 2*i));
			rendpoints.erase(make_pair(interval[i].second.second, 2*i+1));
			ll y = rendpoints.find_by_order(n-i-2)->first;
			temp += f(i,x) -f(i, y);
		
			/* 
			To figure out the change from x_prev to x for items 1 to i-1, 

			Claim: each new point added has its midpoint to the right of the current median
				proof is by induction and using the fact that sorted order of midpoints
				in particular, this means that either one point left of median and one right or two right, so the median never moves back
			If the median stays the same, no change
			If the median moves forward by one point
				if it moved to the left endpoint of point i: no change
				if it moved to any other point: it just moved to prevhighx from prevlowx, so no change
			NO CHANGE FOR ITEMS 1 TO i-1

			To figure out the change for item i: just calculate directly f(i, x) - f(i, oldy)

			To figure out the change for items i+1 to n-1: 
				goes down by f(i, newy) - f(i, oldy): let's see why
					if i was both left of old median and both left of new median: sum wouldn't change if you moved from old to new, but now that we don't factor in the f(i, new) - f(i, old), we have to subtract that
					if i was one left one right of old median and both left of new median: same as above except f(i, old) = 0
					if i was one left one right of old median and one left one right of new median: no change at all, this works

			*/
			// cerr << i << endl;
			// cerr << temp << endl;
			// cerr << endl;
			ans = min(ans, temp);
		}
	}
	cout << ans + pre << endl;
}

Compilation message

bridge.cpp: In function 'void setupIO(std::string)':
bridge.cpp:25:9: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result]
   25 |  freopen((s + ".in").c_str(), "r", stdin);
      |  ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
bridge.cpp:26:9: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result]
   26 |  freopen((s + ".out").c_str(), "w", stdout);
      |  ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Subtask #1
8.0 / 8.0

# Verdict Execution time Memory Grader output
1 Correct 1 ms 364 KB Output is correct
2 Correct 1 ms 364 KB Output is correct
3 Correct 1 ms 492 KB Output is correct
4 Correct 1 ms 492 KB Output is correct
5 Correct 2 ms 492 KB Output is correct
6 Correct 1 ms 492 KB Output is correct
7 Correct 1 ms 492 KB Output is correct
8 Correct 1 ms 492 KB Output is correct
9 Correct 1 ms 492 KB Output is correct
10 Correct 1 ms 492 KB Output is correct
11 Correct 1 ms 492 KB Output is correct

Subtask #2
14.0 / 14.0

# Verdict Execution time Memory Grader output
1 Correct 0 ms 364 KB Output is correct
2 Correct 1 ms 364 KB Output is correct
3 Correct 1 ms 492 KB Output is correct
4 Correct 2 ms 492 KB Output is correct
5 Correct 1 ms 492 KB Output is correct
6 Correct 2 ms 492 KB Output is correct
7 Correct 1 ms 492 KB Output is correct
8 Correct 1 ms 492 KB Output is correct
9 Correct 1 ms 492 KB Output is correct
10 Correct 1 ms 492 KB Output is correct
11 Correct 1 ms 492 KB Output is correct
12 Correct 159 ms 15212 KB Output is correct
13 Correct 227 ms 15212 KB Output is correct
14 Correct 202 ms 13736 KB Output is correct
15 Correct 110 ms 9068 KB Output is correct
16 Correct 195 ms 15360 KB Output is correct
17 Correct 158 ms 15212 KB Output is correct
18 Correct 145 ms 15212 KB Output is correct
19 Correct 167 ms 15272 KB Output is correct
20 Correct 165 ms 15212 KB Output is correct
21 Correct 163 ms 15212 KB Output is correct

Subtask #3
9.0 / 9.0

# Verdict Execution time Memory Grader output
1 Correct 1 ms 364 KB Output is correct
2 Correct 1 ms 364 KB Output is correct
3 Correct 1 ms 364 KB Output is correct
4 Correct 1 ms 364 KB Output is correct
5 Correct 1 ms 364 KB Output is correct
6 Correct 1 ms 364 KB Output is correct
7 Correct 1 ms 364 KB Output is correct
8 Correct 1 ms 364 KB Output is correct
9 Correct 1 ms 364 KB Output is correct
10 Correct 1 ms 364 KB Output is correct
11 Correct 1 ms 364 KB Output is correct
12 Correct 1 ms 364 KB Output is correct

Subtask #4
32.0 / 32.0

# Verdict Execution time Memory Grader output
1 Correct 1 ms 364 KB Output is correct
2 Correct 1 ms 364 KB Output is correct
3 Correct 1 ms 364 KB Output is correct
4 Correct 1 ms 364 KB Output is correct
5 Correct 1 ms 364 KB Output is correct
6 Correct 1 ms 364 KB Output is correct
7 Correct 1 ms 364 KB Output is correct
8 Correct 1 ms 364 KB Output is correct
9 Correct 1 ms 364 KB Output is correct
10 Correct 1 ms 364 KB Output is correct
11 Correct 1 ms 364 KB Output is correct
12 Correct 1 ms 364 KB Output is correct
13 Correct 2 ms 492 KB Output is correct
14 Correct 3 ms 492 KB Output is correct
15 Correct 3 ms 492 KB Output is correct
16 Correct 2 ms 364 KB Output is correct
17 Correct 1 ms 364 KB Output is correct
18 Correct 1 ms 364 KB Output is correct
19 Correct 2 ms 492 KB Output is correct
20 Correct 2 ms 492 KB Output is correct
21 Correct 3 ms 492 KB Output is correct
22 Correct 2 ms 492 KB Output is correct
23 Correct 2 ms 492 KB Output is correct
24 Correct 2 ms 492 KB Output is correct

Subtask #5
37.0 / 37.0

# Verdict Execution time Memory Grader output
1 Correct 1 ms 364 KB Output is correct
2 Correct 1 ms 364 KB Output is correct
3 Correct 1 ms 364 KB Output is correct
4 Correct 1 ms 364 KB Output is correct
5 Correct 1 ms 364 KB Output is correct
6 Correct 1 ms 364 KB Output is correct
7 Correct 1 ms 364 KB Output is correct
8 Correct 1 ms 364 KB Output is correct
9 Correct 1 ms 364 KB Output is correct
10 Correct 1 ms 364 KB Output is correct
11 Correct 1 ms 364 KB Output is correct
12 Correct 1 ms 364 KB Output is correct
13 Correct 2 ms 492 KB Output is correct
14 Correct 2 ms 492 KB Output is correct
15 Correct 2 ms 492 KB Output is correct
16 Correct 1 ms 512 KB Output is correct
17 Correct 1 ms 364 KB Output is correct
18 Correct 1 ms 364 KB Output is correct
19 Correct 3 ms 492 KB Output is correct
20 Correct 2 ms 492 KB Output is correct
21 Correct 2 ms 492 KB Output is correct
22 Correct 2 ms 492 KB Output is correct
23 Correct 2 ms 512 KB Output is correct
24 Correct 2 ms 492 KB Output is correct
25 Correct 370 ms 15468 KB Output is correct
26 Correct 263 ms 15232 KB Output is correct
27 Correct 620 ms 15468 KB Output is correct
28 Correct 656 ms 15340 KB Output is correct
29 Correct 646 ms 15340 KB Output is correct
30 Correct 238 ms 8172 KB Output is correct
31 Correct 440 ms 15212 KB Output is correct
32 Correct 356 ms 15212 KB Output is correct
33 Correct 326 ms 15208 KB Output is correct
34 Correct 357 ms 15416 KB Output is correct
35 Correct 377 ms 15596 KB Output is correct
36 Correct 364 ms 15212 KB Output is correct
37 Correct 359 ms 15212 KB Output is correct