02-线性结构4 Pop Sequence (25分)

02-线性结构4 Pop Sequence   (25分)

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<cstdio> #include<stack> using namespace std; stack<int> st; int main(void) { int pop_stack[1001]={0}; int m,n,k; scanf("%d%d%d",&m,&n,&k); while(k--) { while(!st.empty()) { st.pop(); } for(int i = 1; i <= n; i++) { scanf("%d",&pop_stack[i]); } int count = 1; bool flag = true; for(int i = 1; i <= n; i++) { st.push(i); if(st.size() > m) { flag = false; break; } while(!st.empty()&&st.top() == pop_stack[count]) { st.pop(); count++; } } if(st.empty() == true && flag == true) { printf("YES\n"); } else { printf("NO\n"); } } return 0; }

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