Submission #1022074

#	Time	Username	Problem	Language	Result	Execution time	Memory
1022074		vjudge1	Aliens (IOI16_aliens)	C++17	0 / 100	1 ms	1116 KiB

aliens

#include <bits/stdc++.h>
using namespace std;
typedef long long ll;

const int maxn = 4e3 + 100;

int a[maxn];
int b[maxn];
int c[maxn];
int pref[maxn];
int suf[maxn];
ll dp[maxn][maxn];
vector<int> v;

int get(int i, int j){
	if(!i) return 0;
    ll x = max(0, (- i + a[i] + j + a[j]) / 2);
    return x * x;
}

void calc(int cnt, int l = 1, int r = v.size(), int tl = 1, int tr = v.size()){
	int i = (l + r) >> 1, tm;
	for(int j = tl; j <= min(i, tr); j++){
		ll x = dp[j-1][cnt-1] + get(v[j-1], v[i-1]);
		if(j > 1) x -= get(v[j-1], v[j-2]);
		if(dp[i][cnt] > x){
			dp[i][cnt] = x;
			tm = j;
		}
	}
	if(l < r){
		calc(cnt, l, i, tl, tm);
		calc(cnt, i+1, r, tm, tr);
	}
}

long long take_photos(int n, int m, int k, std::vector<int> r, std::vector<int> c){
	for(int i = 0; i < n; i++){
		r[i]++; c[i]++;
		int x = r[i] + c[i] - 1;
		a[x] = max(a[x], abs(r[i] - c[i]) + 1);
	}
	for(int i = 1; i < m * 2; i++){
		pref[i] = max(pref[i-1] - 1, a[i]);
	}
	for(int i = m * 2 - 1; i > 0; i--){
		suf[i] = max(suf[i+1] - 1, a[i]);
	}
	for(int i = 1; i < m * 2; i++){
		if(max(pref[i-1], suf[i+1]) <= a[i] && a[i]){
			v.push_back(i);
		}
	}
	for(int i = 0; i <= v.size(); i++){
		fill(dp[i], dp[i] + k + 1, (ll)1e18);
	}
	dp[0][0] = 0;
	for(int cnt = 1; cnt <= k; cnt++){
		calc(cnt);
	}
	return *min_element(dp[v.size()], dp[v.size()] + k + 1);
}

Compilation message (stderr)

aliens.cpp: In function 'long long int take_photos(int, int, int, std::vector<int>, std::vector<int>)':
aliens.cpp:54:19: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   54 |  for(int i = 0; i <= v.size(); i++){
      |                 ~~^~~~~~~~~~~
aliens.cpp: In function 'void calc(int, int, int, int, int)':
aliens.cpp:32:7: warning: 'tm' may be used uninitialized in this function [-Wmaybe-uninitialized]
   32 |   calc(cnt, l, i, tl, tm);
      |   ~~~~^~~~~~~~~~~~~~~~~~~

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