Submission #29304

#	Time	Username	Problem	Language	Result	Execution time	Memory
29304		kdh9949	Untitled (POI11_dyn)	C++14	100 / 100	1606 ms	30400 KiB

Main

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

int n, m, d[300010], ans;
vector<int> e[300010];

int f(int x, int p, int c){
	int t = 0, v = 0;
	for(auto &i : e[x]){
		if(i != p){
			int u = f(i, x, c);
			if(!u) continue;
			if(u > 0) v = max(v, u);
			else t = min(t, u);
		}
	}
	if(abs(t) >= c){
		ans++;
		return c;
	}
	if(!v && !t) return -d[x];
	if(v > abs(t)) return v - 1;
	return t - 1;
}

int can(int k){
	ans = 0;
	if(f(1, 0, k) < 0) ans++;
	return ans <= m;
}

int main(){
	scanf("%d%d", &n, &m);
	for(int i = 1; i <= n; i++) scanf("%d", d + i);
	for(int i = 0, x, y; i < n - 1; i++){
		scanf("%d%d", &x, &y);
		e[x].push_back(y);
		e[y].push_back(x);
	}
	if(count(d + 1, d + n + 1, 1) <= m){ puts("0"); return 0; }
	int st = 1, en = n - 1;
	while(st <= en){
		int mi = (st + en) / 2;
		if(can(mi)) en = mi - 1;
		else st = mi + 1;
	}
	printf("%d\n", st);
}

Compilation message (stderr)

dyn.cpp: In function 'int main()':
dyn.cpp:33:23: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
  scanf("%d%d", &n, &m);
                       ^
dyn.cpp:34:48: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
  for(int i = 1; i <= n; i++) scanf("%d", d + i);
                                                ^
dyn.cpp:36:24: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   scanf("%d%d", &x, &y);
                        ^

• Subtask 1: 10 / 10
• Subtask 2: 10 / 10
• Subtask 3: 10 / 10
• Subtask 4: 10 / 10
• Subtask 5: 10 / 10
• Subtask 6: 10 / 10
• Subtask 7: 10 / 10
• Subtask 8: 10 / 10
• Subtask 9: 10 / 10
• Subtask 10: 10 / 10