deque 的插入操作不一定有 vector 快
#include <iostream>#include <cstring>#include <fstream>#include <vector>using namespace std;#define NOT_SELECTED 0#define SELECTED 1#define SIZE 6001vector< int > relations[SIZE];bool visited[SIZE];int DP[SIZE][2];int farents[SIZE];void dfs( int node ){if( visited[node] )return;visited[node] = true;for( int i = 0; i < relations[node].size(); ++i ){int next = relations[node][i];if( !visited[next] ){dfs( next );DP[node][NOT_SELECTED] += max( DP[next][NOT_SELECTED], DP[next][SELECTED] );DP[node][SELECTED]+= DP[next][NOT_SELECTED];}}}int main(){int employees_num;int supervisor, employee;int ans = 0;while( cin >> employees_num ){memset( visited, false, sizeof( visited ) );memset( DP, 0, sizeof( DP ) );memset( farents, 0, sizeof( farents ) );for ( int i = 1; i <= employees_num; ++i ){cin >> DP[i][SELECTED];relations[i].clear();}while( true ){cin >> employee >> supervisor;if( employee == 0 && supervisor == 0 )break;farents[employee] = supervisor;relations[supervisor].push_back( employee );}for( int i = 1; i <= employees_num; ++i ){if( farents[i] == 0 ){dfs( i );int new_ans = max( DP[i][NOT_SELECTED], DP[i][SELECTED] );ans = max( ans, new_ans );}}cout << ans << endl;}return 0;}
，不论你在什么时候开始，重要的是开始之後就不要停止
