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
Sample Output:
YES NO NO YES NO
#include<iostream>
#include<stack>
using namespace std;
const int maxn = 1010;
int check(int *a,int n,int m);
int main()
{
int arr[maxn] = {0};
int n,m,k;
scanf("%d%d%d",&m,&n,&k);
for (int i = 0; i < k; i++)
{
for (int j = 1; j <= n; j++)
{
scanf("%d",&arr[j]);
}
if(check(arr,n,m))
{
printf("YES\n");
}
else
{
printf("NO\n");
}
}
return 0;
}
int check(int *a,int n,int m)
{
int iRet = -1;
stack<int> s;
int current = 1;
bool flag = true;
for (int i = 1; i <= n; i++)
{
s.push(i);
if (s.size() > m)
{
flag = false;
break;
}
while (!s.empty() && a[current] == s.top())
{
current++;
s.pop();
}
}
if (flag && s.empty())
{
iRet = 1;
}
else
{
iRet = 0;
}
return iRet;
}