ZOJ 2954 Hanoi Tower（模拟啊 ）

题目链接：http://acm.zju.edu.cn/onlinejudge/showProblem.do?problemId=1953

You all must know the puzzle named "The Towers of Hanoi". The puzzle has three pegs (peg 1, peg 2 and peg 3) and N disks of different radii. Initially all disks are located on the first
peg, ordered by their radii - the largest at the bottom, the smallest at the top. In each turn you may take the topmost disc from any peg and move it to another peg, the only rule says that you may not place the disc atop any smaller disk. The problem is to
move all disks to the last peg (peg 3). I use two different integers a (1 <= a <= 3) and b (1 <= b <= 3) to indicate a move. It means to move the topmost disk of peg a to the top of peg b. A move is valid
if and only if there is at least one disk on peg a and the topmost disk of peg a can be moved on the peg b without breaking the former rule.

Give you some moves of a game, can you give out the result of the game?

Input

Standard input will contain multiple test cases. The first line of the input is a single integer T (1 <= T <= 55) which is the number of test cases. And it will be followed
byT consecutive test cases.

The first line of each test case is a single line containing 2 integers n (1 <= n <= 10) and m (1 <= m <= 12000) which is the number of disks and the
number of the moves. Then m lines of moves follow.

Output

For each test case, output an integer in a single line according to the result of the moves.

Note:

Sample Input

3
2 3
1 2
1 3
2 3
2 3
1 2
1 3
3 2
2 3
1 3
1 2
3 2

Sample Output

3
-3
0

Source: Zhejiang University Local Contest 2008

代码如下：

#include<cstdio>
#include<stack>
#include<iostream>
using namespace std;
stack<int>s[4];
int ans,flog,p,n,m,t,step,k,i;
int x, y,a,b ,f;
void judge(int a , int b);
int main()
{

    while(~scanf("%d",&t))
    {
        while(t--)
        {
            scanf("%d%d",&n,&m);
            flog = ans = p = k = step = 0;
            for( i = 0 ; i < 4 ; i++ )
            {
                while(!s[i].empty())
                    s[i].pop();
            }
            for(i = n ; i >= 1 ; i--)
                s[1].push(i);
            for(i = 1 ; i <= m ; i++ )
            {
                scanf("%d%d",&a,&b);
                if(flog)
                    continue;
                ans++;
                if(s[a].empty() == 1)
                {
                    flog = 1;
                    step = ans;
                    continue;
                }
                judge(a , b);
                if(s[3].size()==n)
                {
                    flog = 2;
                    step = ans;
                }
            }
            if(flog == 1)
                printf("-%d\n",step);
            else if(s[3].size() == n)
                printf("%d\n",step);
            else
                printf("0\n");
        }
    }
    return 0;
}

void judge(int a , int b)
{
    x = s[a].top();
    if(s[b].empty() == 1)
    {
        s[b].push(x);
        s[a].pop();
        return;
    }
    else
        y = s[b].top();
    if(x > y)
    {
        flog = 1;
        step = ans;
        return;
    }
    else
    {
        s[b].push(x);
        s[a].pop();
    }
}