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
队列+栈 模拟
AC代码
#include<iostream>
#include<stack>
#include<queue>
using namespace std;
int capacity;
int sequence;
int t;
int out[1100];
void clear_q(queue<int>& q) {
queue<int> empty;
swap(empty, q);
}
void clear_s(stack<int>& q) {
stack <int> empty;
swap(empty, q);
}
int main() {
// freopen("aa.txt","r",stdin);
cin >> capacity >> sequence >> t;
int a;
stack <int> s;
queue<int> q_begin;
queue<int> q_end;
while(t--){
clear_s(s);
clear_q(q_begin);
clear_q(q_end);
for(int i = 1;i <= sequence;i++){
cin >> a;
q_begin.push(i);
q_end.push(a);
}
int count = 1;
while(!q_end.empty()){
if(!count){
break;
}
int n1 = q_end.front();
int n2;
int yes = 0;
q_end.pop();
if(s.size()!=0){
n2 = s.top();
if(n2 == n1){
yes = 1;
s.pop();
}else{
int yes2 = 0;
int yes3 = 0;
while(!q_begin.empty()){
if(yes2){
break;
}
int n3 = q_begin.front();
q_begin.pop();
if(n3 == n1){
yes2 = 1;
yes3 = 1;
if(s.size() == capacity){
count = 0;
}
}else{
s.push(n3);
if(s.size() > capacity){
count = 0;
yes2 = 1;
}
}
}
if(!yes3){
count = 0;
}
}
}else{
int yes2 = 0;
int yes3 = 0;
while(!q_begin.empty()){
if(yes2){
break;
}
int n3 = q_begin.front();
q_begin.pop();
if(n3 == n1){
yes2 = 1;
yes3 = 1;
if(s.size() == capacity){
count = 0;
}
}else{
s.push(n3);
if(s.size() > capacity){
count = 0;
yes2 = 1;
}
}
}
if(!yes3){
count = 0;
}
}
}
if(q_end.size()!=0){
count = 0;
}
if(count){
cout << "YES" << endl;
}else{
cout << "NO" << endl;
}
}
return 0;
}