oj.uz

Submission #26726

# Submission time Handle Problem Language Result Execution time Memory
26726 2017-07-05T10:29:20 Z model_code Dynamite (POI11_dyn) C++14
100 / 100
 2256 ms 26296 KB 
/*************************************************************************
 *                                                                       *
 *                    XVIII Olimpiada Informatyczna                      *
 *                                                                       *
 *   Zadanie:           Dynamit                                          *
 *   Autor:             Mateusz Baranowski                               *
 *   Zlozonosc czasowa: O(n * lg(n))                                     *
 *   Opis:              Rozwiazanie wzorcowe                             *
 *                      Binarnie wyszukujemy minimalnego czasu, w ktorym *
 *                      mozemy wysadzic ladunki                          *
 *                                                                       *
 *************************************************************************/

#include <cstdio>
#include <vector>
#include <queue>
using namespace std;

#define MAX_N 300000

int n, m;	/* ilosc komor i liczba miejsc, w ktorych mozemy podpalic lont */
int d[MAX_N + 1];	/* d[i] == 0 wtw., gdy w i-tej komorze nie ma dynamitu */
vector<int> korytarze[MAX_N + 1];	/* opis siec komor */ 

queue<int> q;	/* pomocnicza kolejka */
int a, b, c, i, j, p, x;	/* zmienne pomocnicze */
int z[MAX_N + 1];	/* tablice pomocnicze */
int min_tab[MAX_N + 1], max_tab[MAX_N + 1]; 
/* ile minimalnie w dol, ile maksymalnie w gore */

/* wczytaj() - wczytuje dane i zmienia reprezentacje sieci komor.   * 
 * t[] bedzie zawierala listy sasiedztw kolejnych komor.            * 
 * Konce kolejnych list zapamietamy w k[].                          */
void wczytaj() {
	scanf ("%d %d", &n, &m);
	x = 0;
	for (i = 1; i <= n; ++i) {
		scanf ("%d", &d[i]);
		korytarze[i].clear();
		x += d[i];
	}
	
	for (i = 1; i < n; ++i) {
		scanf ("%d %d", &a, &b);
		korytarze[a].push_back(b);
		korytarze[b].push_back(a);
	}
}


/* sprawdz(x) - sprawdza, czy jestesmy w stanie wysadzic wszystkie   *
 * dynamity w x jednostkach czasu.                                   */
int sprawdz(int czas) {
	/* wyznaczamy liscie i wrzucamy na statyczna kolejke q */
	//printf ("czas :%d\n", czas);
	while (!q.empty())
		q.pop();
	for (i = 1; i <= n; ++i) {
		min_tab[i] = 0;
		max_tab[i] = 0;
		z[i] = korytarze[i].size();
		if (z[i] == 1)
			q.push(i);
	}
	
	j = m;
	/* wyznaczamy miejsca, w ktorych musimy podpalic lont */
	while ((j >= 0) && (!q.empty())) {
		p = q.front();
		q.pop();
		if (max_tab[p] > -min_tab[p]) /* zapali sie od poprzedniego lontu */
			min_tab[p] = 0;
		else if (min_tab[p] == -czas) { /* musimy podpalic lont */
			--j;
			max_tab[p] = czas + 1;
			min_tab[p] = 0;
		}

		for (size_t i = 0; i < korytarze[p].size(); ++i) {
			x = korytarze[p][i];
			if (z[x] > 0) {
				if (max_tab[x] < max_tab[p] - 1)
					max_tab[x] = max_tab[p] - 1;

				if ((min_tab[p] < 0) || ((max_tab[p] == 0) && (d[p] == 1)))
					if (min_tab[x] > min_tab[p] - 1)
						min_tab[x] = min_tab[p] - 1;

				if (--z[x] == 1)
					q.push(x);
			}
		}
	}

	/* sprawdzamy, czy w ostatnim rozwazanym wierzcholku nalezy zapalic lont */
	if (j >= 0)
		if ((min_tab[p] < 0) || ((max_tab[p] == 0) && (d[p] == 1)))
			--j;
	
	/* jezeli nie podpalilismy za duzo lontow i przetworzylismy cale drzewo *
	 * to mozna w [czas] jednostek czasu podpalic wszystkie dynamity        */
	return ((j >= 0) && (q.empty())); 
}


/*****************************  MAIN  ************************************/
int main() {
	wczytaj();
	
	if (x <= m) {
		printf ("0\n");
		return 0;
	}

	/* binarne wyszukiwanie wyniku */
	a = 1;
	b = n / 2;
	while (a < b) {
		c = (a + b) / 2;
		
		if (sprawdz (c))
			b = c;
		else
			a = c + 1;
	}

	printf ("%d\n", a);

	return 0;
}

Compilation message

dyn.cpp: In function 'void wczytaj()':
dyn.cpp:35:25: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
  scanf ("%d %d", &n, &m);
                         ^
dyn.cpp:38:22: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   scanf ("%d", &d[i]);
                      ^
dyn.cpp:44:26: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   scanf ("%d %d", &a, &b);
                          ^

Subtask #1
10.0 / 10.0

# Verdict Execution time Memory Grader output
1 Correct 6 ms 13652 KB Output is correct
2 Correct 0 ms 13652 KB Output is correct
3 Correct 3 ms 13652 KB Output is correct
4 Correct 0 ms 13652 KB Output is correct

Subtask #2
10.0 / 10.0

# Verdict Execution time Memory Grader output
1 Correct 0 ms 13652 KB Output is correct
2 Correct 3 ms 13652 KB Output is correct
3 Correct 0 ms 13652 KB Output is correct

Subtask #3
10.0 / 10.0

# Verdict Execution time Memory Grader output
1 Correct 0 ms 13652 KB Output is correct
2 Correct 0 ms 13652 KB Output is correct

Subtask #4
10.0 / 10.0

# Verdict Execution time Memory Grader output
1 Correct 3 ms 13652 KB Output is correct
2 Correct 0 ms 13652 KB Output is correct

Subtask #5
10.0 / 10.0

# Verdict Execution time Memory Grader output
1 Correct 6 ms 14048 KB Output is correct
2 Correct 29 ms 14444 KB Output is correct
3 Correct 49 ms 14708 KB Output is correct
4 Correct 39 ms 14576 KB Output is correct

Subtask #6
10.0 / 10.0

# Verdict Execution time Memory Grader output
1 Correct 79 ms 15632 KB Output is correct
2 Correct 136 ms 16160 KB Output is correct
3 Correct 259 ms 16292 KB Output is correct
4 Correct 223 ms 16160 KB Output is correct

Subtask #7
10.0 / 10.0

# Verdict Execution time Memory Grader output
1 Correct 333 ms 17348 KB Output is correct
2 Correct 323 ms 17352 KB Output is correct
3 Correct 316 ms 16820 KB Output is correct
4 Correct 339 ms 17348 KB Output is correct

Subtask #8
10.0 / 10.0

# Verdict Execution time Memory Grader output
1 Correct 1053 ms 20568 KB Output is correct
2 Correct 1256 ms 21984 KB Output is correct
3 Correct 1506 ms 21836 KB Output is correct
4 Correct 1643 ms 21836 KB Output is correct

Subtask #9
10.0 / 10.0

# Verdict Execution time Memory Grader output
1 Correct 2243 ms 23420 KB Output is correct
2 Correct 1816 ms 24624 KB Output is correct
3 Correct 2256 ms 23420 KB Output is correct

Subtask #10
10.0 / 10.0

# Verdict Execution time Memory Grader output
1 Correct 1726 ms 23684 KB Output is correct
2 Correct 1343 ms 24628 KB Output is correct
3 Correct 2213 ms 23288 KB Output is correct
4 Correct 833 ms 26296 KB Output is correct