浙江大学数据结构: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

提测代码：

#include <stdio.h>
#include <stdlib.h>

#define ERROR -1
typedef int Position;
typedef int ElemType;
struct SNode{
    ElemType* Data;
    Position Top;
    int MaxSize;
};

typedef struct SNode *Stack;

Stack CreateStack(int MaxSize){
    Stack S = (Stack)malloc(sizeof(struct SNode));
    S->Data = (ElemType*)malloc(MaxSize * sizeof(ElemType));
    S->Top = -1;
    S->MaxSize = MaxSize;
    return S;
}

void DestroyStack(Stack S){
    if(S == NULL){
        return;
    }
    if(S->Data != NULL){
        free(S->Data);
    }
    free(S);
}

int IsEmpty(Stack S){
    return (S->Top == -1);
}

int IsFull(Stack S){
    return (S->Top + 1 == S->MaxSize);
}

int Push(Stack S, ElemType data){
    if(IsFull(S)){
        return ERROR;
    }
    S->Data[++S->Top] = data;
    return 1;
}

ElemType Pop(Stack S){
    if(IsEmpty(S)){
        return ERROR;
    }
    return S->Data[S->Top--];
}

void Empty(Stack S){
    S->Top = -1;
}


int main(){
    int M, N, line;
    scanf("%d %d %d", &M, &N, &line);
    ElemType curData;
    int countor;
    int flag;
    Stack S = CreateStack(M);
    for(int i = 0; i < line; ++i){
        countor = 1;
        flag = 1;
　　　　　Empty(S);
        for(int j = 0; j < N; ++j){
            scanf("%d", &curData);
            if(!flag)
                continue;
            //如果计数器小于当前值
            if(countor < curData){
                while(countor <= curData){
                    if(Push(S, countor++) == ERROR){
                        flag = 0;
                        break;
                    }
                }
                Pop(S);
            }
            else if(countor > curData){
                if(Pop(S) != curData){
                    flag = 0;
                }
            }
            else{
                countor++;
            }
        }
        if(flag == 1 && IsEmpty(S)){
            printf("YES
");
        }
        else{
            printf("NO
");
        }
    }
    return 0;
}

 提测结果：