Submission #16212

#	Time	Username	Problem	Language	Result	Execution time	Memory
16212		makesource	Beads and wires (APIO14_beads)	C++98	100 / 100	406 ms	30312 KiB

beads

//
//  main.cpp
//  apioC
//
//  Created by 방성원 on 2015. 8. 16..
//  Copyright (c) 2015년 makesource. All rights reserved.
//
#include <stdio.h>
#include <vector>
#include <algorithm>
#include <memory.h>
#define max(a,b) ((a)>(b)?(a):(b))
#define __ 200020
using namespace std;

vector<int> g[__], length[__];
int red[__], blue[__], vis[__], second[__], pos[__];
int n, ans;

void dfs(int node,int parent,int len) {
    vis[node] = 1;
    for (int i=0;i<g[node].size();i++) {
        if (vis[g[node][i]]) continue;
        dfs(g[node][i],node,length[node][i]);
    }
    
    for (int i=0;i<g[node].size();i++) {
        if(g[node][i] == parent) continue;
        red[node] += max(red[g[node][i]],blue[g[node][i]]);
    }
    for (int i=0;i<g[node].size();i++) {
        if(g[node][i] == parent) continue;
        int value=max(red[g[node][i]],blue[g[node][i]]);
        blue[node] = max(blue[node],red[node]-value+red[g[node][i]]+length[node][i]+len);
    }
}

void changeRoot(int node,int parent) {
    int rr = red[node];
    int bb = blue[node];
    vis[node] = 1;
    
    red[node] = 0; blue[node] = 0;
    for (int i=0;i<g[node].size();i++) {
        red[node] += max(red[g[node][i]],blue[g[node][i]]);
    }
    for (int i=0;i<g[node].size();i++) {
        
        int value=max(red[g[node][i]],blue[g[node][i]]);
        
        if (blue[node] < red[node]-value+red[g[node][i]]+length[node][i]) {
            second[node] = max(second[node],blue[node]);
            blue[node] = red[node]-value+red[g[node][i]]+length[node][i];
            pos[node] = i;
        } else {
            second[node] = max(second[node],red[node]-value+red[g[node][i]]+length[node][i]);
        }
    }
    int nowRed = red[node];
    int nowBlue = blue[node];
    ans = max(ans,nowRed);
    
    for (int i=0;i<g[node].size();i++) {
        if (vis[g[node][i]]) continue;
        red[node] = nowRed; blue[node] = nowBlue;
        
        red[node] -= max(red[g[node][i]],blue[g[node][i]]);
        if(pos[node] != i) {
            blue[node] -= max(red[g[node][i]],blue[g[node][i]]);
        } else {
            blue[node] = second[node];
            blue[node] -= max(red[g[node][i]],blue[g[node][i]]);
        }
        blue[node] += length[node][i];
        changeRoot(g[node][i],node);
    }
    
    red[node] = rr;
    blue[node] = bb;
    
   
}

int main() {
    scanf("%d",&n);
    for(int i=1;i<n;i++) {
        int a,b,c;
        scanf("%d%d%d",&a,&b,&c);
        g[a].push_back(b); length[a].push_back(c);
        g[b].push_back(a); length[b].push_back(c);
    }
    dfs(1,-1,0);
    memset(vis,0,sizeof vis);
    changeRoot(1,-1);
    printf("%d",ans);
    return 0;
}

Compilation message (stderr)

beads.cpp: In function 'void dfs(int, int, int)':
beads.cpp:22:19: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
     for (int i=0;i<g[node].size();i++) {
                  ~^~~~~~~~~~~~~~~
beads.cpp:27:19: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
     for (int i=0;i<g[node].size();i++) {
                  ~^~~~~~~~~~~~~~~
beads.cpp:31:19: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
     for (int i=0;i<g[node].size();i++) {
                  ~^~~~~~~~~~~~~~~
beads.cpp: In function 'void changeRoot(int, int)':
beads.cpp:44:19: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
     for (int i=0;i<g[node].size();i++) {
                  ~^~~~~~~~~~~~~~~
beads.cpp:47:19: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
     for (int i=0;i<g[node].size();i++) {
                  ~^~~~~~~~~~~~~~~
beads.cpp:63:19: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
     for (int i=0;i<g[node].size();i++) {
                  ~^~~~~~~~~~~~~~~
beads.cpp: In function 'int main()':
beads.cpp:85:10: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
     scanf("%d",&n);
     ~~~~~^~~~~~~~~
beads.cpp:88:14: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
         scanf("%d%d%d",&a,&b,&c);
         ~~~~~^~~~~~~~~~~~~~~~~~~

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