Submission #124875

#	Time	Username	Problem	Language	Result	Execution time	Memory
124875		nvmdava	Aliens (IOI16_aliens)	C++17	60 / 100	2045 ms	6376 KiB

aliens

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

vector<pair<int, int> > v, t;

long long dp[2][100005];

long long cost(int l, int r){
	l++;
	if(l > r) return 0;
	long long t1 = v[r].second - v[l].first;
	long long t2 = max(0, v[l - 1].second - v[l].first);
	return t1 * t1 - t2 * t2;
}

void opt(int id, int l, int r, int optl, int optr){
	if(l > r) return;
	int m = (l + r) >> 1;
	dp[id][m] = 0x3f3f3f3f3f3f3f3f;
	int optm;
	for(int o = optl; o <= min(m, optr); o++){
		long long c = cost(o, m);
		if(dp[id][m] >= dp[id ^ 1][o] + c){
			dp[id][m] = dp[id ^ 1][o] + c;
			optm = o;
		}
	}
	opt(id, l, m - 1, optl, optm);
	opt(id, m + 1, r, optm, optr);
}

long long take_photos(int n, int m, int k, vector<int> r, vector<int> c){
	
    for(int i = 0; i < n; i++)
    	t.push_back({min(r[i], c[i]), max(c[i], r[i]) + 1});
	sort(t.begin(), t.end());
	int mx = -1;
	v.push_back({-1, -1});
	for(auto& x : t)
		if(x.second > mx)
			v.push_back({x.first, mx = x.second});
	
	n = v.size() - 1;
	k = min(k, n);
	
	memset(dp, 0x3f3f, sizeof dp);
	dp[0][0] = 0;
	
	for(int i = 1; i <= k; i++){
		opt(i & 1, 0, n, 0, n);
	}
	return dp[k & 1][n];
}

Compilation message (stderr)

aliens.cpp: In function 'long long int take_photos(int, int, int, std::vector<int>, std::vector<int>)':
aliens.cpp:35:5: warning: this 'for' clause does not guard... [-Wmisleading-indentation]
     for(int i = 0; i < n; i++)
     ^~~
aliens.cpp:37:2: note: ...this statement, but the latter is misleadingly indented as if it were guarded by the 'for'
  sort(t.begin(), t.end());
  ^~~~
aliens.cpp: In function 'void opt(int, int, int, int, int)':
aliens.cpp:29:5: warning: 'optm' may be used uninitialized in this function [-Wmaybe-uninitialized]
  opt(id, l, m - 1, optl, optm);
  ~~~^~~~~~~~~~~~~~~~~~~~~~~~~~

• Subtask 1: 4 / 4
• Subtask 2: 12 / 12
• Subtask 3: 9 / 9
• Subtask 4: 16 / 16
• Subtask 5: 19 / 19
• Subtask 6: 0 / 40