Given a stack which can keep M numbers at most. Push N numbers in the order of 1, 2, 3, ..., N and pop randomly. You are supposed to tell if a given sequence of numbers is a possible pop sequence of the stack. For example, if M is 5 and N is 7, we can obtain 1, 2, 3, 4, 5, 6, 7 from the stack, but not 3, 2, 1, 7, 5, 6, 4.
Input Specification:
Each input file contains one test case. For each case, the first line contains 3 numbers (all no more than 1000): M (the maximum capacity of the stack), N (the length of push sequence), and K (the number of pop sequences to be checked). Then K lines follow, each contains a pop sequence of N numbers. All the numbers in a line are separated by a space.
Output Specification:
For each pop sequence, print in one line "YES" if it is indeed a possible pop sequence of the stack, or "NO" if not.
Sample Input:
5 7 5
1 2 3 4 5 6 7
3 2 1 7 5 6 4
7 6 5 4 3 2 1
5 6 4 3 7 2 1
1 7 6 5 4 3 2
结尾无空行
Sample Output:
YES
NO
NO
YES
NO
结尾无空行
代码：
#include <stack>
#include <iostream>
using namespace std;
int main()
{
int m, n, k;
cin >> m >> n >> k;
stack<int> stack;
bool Flag;
while (k--)
{
int j = 1;
int l;
Flag = true;
for (int i = 1; i <= n; i++)
{
if (!Flag)
{
cin >> l;
continue;
}
else
cin >> l;
if ( stack.empty() || l != stack.top())
{
for( ; j <= l ; j++)
stack.push(j);
}
if (stack.size() > m || stack.top() != l)
Flag = false;
else if(stack.top()== l)
stack.pop();
}
if (Flag)
cout << "YES" << endl;
else
cout << "NO" << endl;
while (!stack.empty())
stack.pop();
}
return 0;
}
