题目详情：
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简单翻译：
本题就是告诉你一个最大空间为m的堆栈，往这个堆栈里面依次加入1~n的数字，再给n个测试顺序，判断每个顺序能否实现
主要思路：
建立一个辅助栈，想这个辅助栈里压入1~n
给出的顺序无法实现有两种情况，一种是栈的空间不够大，比如栈的空间是5，给7 6 5 4 3 2 1就不能；一种是顺序问题
外层循环遍历从1~n，如果栈没有满，就压入栈
内层循环判断栈顶元素和cur指针当前所指元素是否相同，如果相同，就弹出栈顶元素，并且cur指针指向下一位
最后如果反应循环过程中栈没满的flag为true和辅助栈最后为空，说明该序列合法
原理……还没想好
第一次写错误：
判断栈有没有满不能用MAX_SIZE，而要定义一个全局变量读入题干所给的M
代码实现：
#include <stdio.h>
#include <stdbool.h>
#define MAX_SIZE 1005
#define EMPTY -1
/*实现栈的数据结构*/
typedef struct StackNode Stack;
struct StackNode {int Data[MAX_SIZE];int Top;
};/*栈的初始化*/
void InitStack(Stack* stackName) {(*stackName).Top = -1;return;
}
/*检测栈有没有满,返回false是没满，返回true是满了*/
int CAPACITY;
bool IsFull(Stack* stackName) {bool ret = false;if((*stackName).Top == CAPACITY - 1) ret = true;return ret;
}/*检测栈是不是为空,返回true就是空，返回false就是不空*/
bool IsEmpyt(Stack* stackName) {bool ret = false;if((*stackName).Top == EMPTY) ret = true;return ret;
}/*向栈里加入元素*/
void Push(Stack* stackName, int data) {if(IsFull(stackName)) {return;}int position = (*stackName).Top;(*stackName).Data[++position] = data;(*stackName).Top = position;return;
}/*从栈里弹出元素*/
void Pop(Stack* stackName) {if(IsEmpyt(stackName)) {return;}int topPosition = (*stackName).Top;int topData = (*stackName).Data[topPosition--];(*stackName).Top = topPosition;
}/*访问栈顶元素*/
int Top(Stack* stackName) {if(IsEmpyt(stackName)) {return EMPTY;}return (*stackName).Data[(*stackName).Top];
}
/*读入待判断数据，返回判断结果*/
bool Judge(const int* num, int dataLength) {Stack s;InitStack(&s);int cur = 0;bool flag = true;for(int i = 1; i <= dataLength; i++) {if(!IsFull(&s)) {Push(&s, i);}else {flag = false;break;}while(!IsEmpyt(&s) && num[cur] == Top(&s)) {Pop(&s);cur++;}}if(flag == true && IsEmpyt(&s)) {return true;}else return false;
}
int main() {int N, K; //M (the maximum capacity of the stack), N (the length of push sequence), and K (the number of pop sequences to be checked). scanf("%d %d %d", &CAPACITY, &N, &K);int num[N];for(int i = 0; i < K; i++) {for(int j = 0; j < N; j++) {scanf("%d", &(num[j]));}if(Judge(num, N)) {printf("YES\n");}else {printf("NO\n"); }}return 0;
}
