uva 804 Petri Net 模拟

原题

普通的模拟题, 题目虽然比较长但流程还是比较简单的, 所以主要还是几个细节的问题处理好就行了。

注意如果所给数据只能进行N轮循环， 而要求的循环数NF正好等于N时，执行完N轮退出时的状态仍然是alive，虽然下一步已经没有操作可做了。

奇怪的是一开始不知道为啥超时了，然后似乎没改进什么复杂度只改了几个细节再交上去就AC了。。。

以下为AC代码：

#include <iostream>
#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <cmath>
#include <algorithm>
#include <string>
#include <vector>
#include <set>
#include <stack>
#include <queue>
#include <deque>
#include <map>
#include <list>
#include <cassert>
#include <iomanip>

#pragma warning(disable:4996) //关掉4996警告

/*
Uva 804  佩特里网络模拟

*/

using namespace std;

struct Transit {
vector<int> from;
vector<int> to;
};
vector<int> Places(1024);
vector<Transit> Transits(1024);

int NT, NP, NF, Case = 0;

inline bool isAlive(int n) {
bool isEnable = true;
map<int, int> need;
for ( int j = 0; j < Transits
.from.size( ); j++ ) {
need[Transits
.from[j]] += 1;
if ( Places[Transits
.from[j]] < need[Transits
.from[j]] ) {
isEnable = false;
break;
}
}
return isEnable;
}

int Simulate(int times, bool & alive) {
int tmp = times;
while ( times-- ) {
int i = 0;
for ( i = 1; i <= NT; i++ ) {
if ( isAlive(i) ) {
for ( int j = 0; j < Transits[i].from.size( ); j++ ) {
Places[Transits[i].from[j]]--;
}
for ( int j = 0; j < Transits[i].to.size( ); j++ ) {
Places[Transits[i].to[j]]++;
}
break;                              // 完成一次Trans
}
}
if ( i > NT ) {
alive = false;
break;          // Dead
}
}
return (tmp - (times + 1));
}

int main( ) {
//freopen("input.txt", "r", stdin);
//freopen("VSoutput.txt", "w", stdout);
while ( cin >> NP && NP > 0 ) {
Places.clear( );
Transits.clear( );
Places.resize(1024);
for ( int i = 1, tmp; i <= NP; i++ ) {
cin >> tmp;
Places[i] = tmp;
}
cin >> NT;
Transits.resize(1024);
for ( int i = 1, tmp; i <= NT; i++ ) {
while ( cin >> tmp && tmp != 0 ) {
if ( tmp < 0 ) Transits[i].from.push_back(-tmp);
else Transits[i].to.push_back(tmp);
}
}
cin >> NF;
bool alive = true;
int turns = Simulate(NF, alive);
printf("Case %d: %s after %d transitions\n",
++Case, (alive ? "still live" : "dead"), turns);
printf("Places with tokens:");
for ( int i = 1; i <= NP; i++ ) {
if ( Places[i] ) {
printf(" %d (%d)", i, Places[i]);
}
}
cout << endl << endl;
}
//system("pause");
return 0;
}