Submission #88910

#	Submission time	Handle	Problem	Language	Result	Execution time	Memory
88910	2018-12-09T19:02:02 Z	sailormoon	Triumphal arch (POI13_luk)	C++14	100 / 100	1215 ms	39484 KB

#include <string>
#include <algorithm>
#include <iostream>
#include <vector>

using namespace std;
int can_handle(int v, int crs, bool visited[]);
vector<vector<int>> graph (1000001); // size

int main() { 
  int n, a, b, start = 0, midpoint, end, cities; // n -> towns, a -> from, b -> to
  scanf("%d", &n);
  end = n; // last point

  for (int i = 1; i < n; i++) {
    scanf("%d %d", &a, &b);
    graph[a].push_back(b);
    graph[b].push_back(a);
  }

  // binary search for sufficient amount of crews
  while (start < end) {
    bool visited[1000001];
    midpoint = (start + end) / 2;
    for (int i = 1; i <= n; i++) visited[i] = false; // clear array 
    if (can_handle(1, midpoint, visited) == 0) end = midpoint;
    else start = ++midpoint; 
  }
  printf("%d\n", start);
  return 0;
}

int can_handle(int v, int crs, bool visited[]) {
  int num_children = 0, need_crews = 0;
  visited[v] = true;
  for (int i = 0; i < graph[v].size(); i++) {
    int cur = graph[v][i];
    if (!visited[cur]) { 
      num_children++;
      need_crews += can_handle(cur, crs, visited);
    }
  }
  if (num_children + need_crews - crs <= 0)
    return 0;
  return num_children + need_crews - crs;
}

Compilation message

luk.cpp: In function 'int main()':
luk.cpp:11:42: warning: unused variable 'cities' [-Wunused-variable]
   int n, a, b, start = 0, midpoint, end, cities; // n -> towns, a -> from, b -> to
                                          ^~~~~~
luk.cpp: In function 'int can_handle(int, int, bool*)':
luk.cpp:36:21: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
   for (int i = 0; i < graph[v].size(); i++) {
                   ~~^~~~~~~~~~~~~~~~~
luk.cpp: In function 'int main()':
luk.cpp:12:8: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   scanf("%d", &n);
   ~~~~~^~~~~~~~~~
luk.cpp:16:10: 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	24 ms	23928 KB	Output is correct
2	Correct	25 ms	23932 KB	Output is correct
3	Correct	27 ms	23932 KB	Output is correct

Subtask #2
10.0 / 10.0

#	Verdict	Execution time	Memory	Grader output
1	Correct	26 ms	23932 KB	Output is correct
2	Correct	27 ms	23932 KB	Output is correct
3	Correct	25 ms	24036 KB	Output is correct
4	Correct	25 ms	24036 KB	Output is correct
5	Correct	25 ms	24140 KB	Output is correct

Subtask #3
10.0 / 10.0

#	Verdict	Execution time	Memory	Grader output
1	Correct	24 ms	24140 KB	Output is correct
2	Correct	27 ms	24140 KB	Output is correct
3	Correct	25 ms	24140 KB	Output is correct

Subtask #4
10.0 / 10.0

#	Verdict	Execution time	Memory	Grader output
1	Correct	28 ms	24140 KB	Output is correct
2	Correct	28 ms	24140 KB	Output is correct
3	Correct	30 ms	24140 KB	Output is correct

Subtask #5
10.0 / 10.0

#	Verdict	Execution time	Memory	Grader output
1	Correct	35 ms	24556 KB	Output is correct
2	Correct	36 ms	24556 KB	Output is correct
3	Correct	30 ms	24556 KB	Output is correct

Subtask #6
10.0 / 10.0

#	Verdict	Execution time	Memory	Grader output
1	Correct	65 ms	25212 KB	Output is correct
2	Correct	60 ms	25980 KB	Output is correct
3	Correct	43 ms	25980 KB	Output is correct

Subtask #7
10.0 / 10.0

#	Verdict	Execution time	Memory	Grader output
1	Correct	172 ms	27540 KB	Output is correct
2	Correct	171 ms	29368 KB	Output is correct
3	Correct	88 ms	29368 KB	Output is correct

Subtask #8
10.0 / 10.0

#	Verdict	Execution time	Memory	Grader output
1	Correct	600 ms	30944 KB	Output is correct
2	Correct	554 ms	35464 KB	Output is correct
3	Correct	219 ms	35464 KB	Output is correct

Subtask #9
10.0 / 10.0

#	Verdict	Execution time	Memory	Grader output
1	Correct	969 ms	35464 KB	Output is correct

Subtask #10
10.0 / 10.0

#	Verdict	Execution time	Memory	Grader output
1	Correct	1047 ms	35464 KB	Output is correct
2	Correct	1215 ms	39484 KB	Output is correct
3	Correct	419 ms	39484 KB	Output is correct