Submission #17263

#	Time	Username	Problem	Language	Result	Execution time	Memory
17263		gs14004	Beads and wires (APIO14_beads)	C++14	100 / 100	332 ms	23280 KiB

beads

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <math.h>
#include <limits.h>
#include <stack>
#include <queue>
#include <map>
#include <set>
#include <algorithm>
#include <string>
#include <functional>
#include <vector>
#include <numeric>
#include <deque>
#include <utility>
#include <bitset>
#include <iostream>
using namespace std;
typedef long long lint;
typedef long double llf;
typedef pair<int, int> pi;

int n;
vector<pi> graph[200005];
int dp[200005][4];

int f(int x, int m, int p){
	if(~dp[x][m]) return dp[x][m];
	if(m >= 2){
		int maxv = -1e9, sum = 0;
		for(int i=0; i<graph[x].size(); i++){
			int pos = graph[x][i].second;
			if(pos == p) continue;
			int tmp = max(f(pos, 1, x), f(pos, 3, x) + graph[x][i].first);
			sum += tmp;
			maxv = max(maxv, f(pos, m-2, x) + graph[x][i].first - tmp);
		}
		return dp[x][m] = sum + maxv;
	}
	else if(m == 1){
		int ret = 0;
		for(int i=0; i<graph[x].size(); i++){
			int pos = graph[x][i].second;
			if(pos == p) continue;
			ret += max(f(pos, 1, x), f(pos, 3, x) + graph[x][i].first);
		}
		return dp[x][m] = ret;
	}
	else{
		int sum = 0, maxv = 0;
		for(int i=0; i<graph[x].size(); i++){
			int pos = graph[x][i].second;
			if(pos == p) continue;
			int tmp1 = max(f(pos, 1, x), f(pos, 3, x) + graph[x][i].first);
			int tmp2 = max(f(pos, 0, x), f(pos, 2, x) + graph[x][i].first);
			sum += tmp1;
			maxv = max(maxv, tmp2 - tmp1);
		}
		int ret = sum + maxv;
		vector<pi> tmp;
		sum = 0;
		for(int i=0; i<graph[x].size(); i++){
			int pos = graph[x][i].second;
			if(pos == p) continue;
			int tmp1 = max(f(pos, 1, x), f(pos, 3, x) + graph[x][i].first);
			int tmp2 = f(pos, 0, x) + graph[x][i].first; 
			int tmp3 = f(pos, 1, x) + graph[x][i].first; 
			tmp.push_back(pi(tmp2 - tmp1, tmp3 - tmp1));
			sum += tmp1;
		}
		int pmax = -1e9, smax = -1e9;
		for(int i=0; i<tmp.size(); i++){
			ret = max(ret, sum + tmp[i].first + pmax);
			pmax = max(pmax, tmp[i].second);
		}
		for(int i=tmp.size()-1; i>=0; i--){
			ret = max(ret, sum + tmp[i].first + smax);
			smax = max(smax, tmp[i].second);
		}
		return dp[x][m] = ret;
	}
}
int main(){
	memset(dp,-1,sizeof(dp));
	scanf("%d",&n);
	for(int i=0; i<n-1; i++){
		int s, e, x;
		scanf("%d %d %d",&s,&e,&x);
		graph[s].push_back(pi(x, e));
		graph[e].push_back(pi(x, s));
	}
	printf("%d",f(1, 0, 0));
}

Compilation message (stderr)

beads.cpp: In function 'int f(int, int, int)':
beads.cpp:32:17: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
   for(int i=0; i<graph[x].size(); i++){
                ~^~~~~~~~~~~~~~~~
beads.cpp:43:17: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
   for(int i=0; i<graph[x].size(); i++){
                ~^~~~~~~~~~~~~~~~
beads.cpp:52:17: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
   for(int i=0; i<graph[x].size(); i++){
                ~^~~~~~~~~~~~~~~~
beads.cpp:63:17: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
   for(int i=0; i<graph[x].size(); i++){
                ~^~~~~~~~~~~~~~~~
beads.cpp:73:17: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
   for(int i=0; i<tmp.size(); i++){
                ~^~~~~~~~~~~
beads.cpp: In function 'int main()':
beads.cpp:86:7: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
  scanf("%d",&n);
  ~~~~~^~~~~~~~~
beads.cpp:89:8: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   scanf("%d %d %d",&s,&e,&x);
   ~~~~~^~~~~~~~~~~~~~~~~~~~~

• Subtask 1: 13 / 13
• Subtask 2: 15 / 15
• Subtask 3: 29 / 29
• Subtask 4: 43 / 43