6、栈

1、顺序栈

#include<stdio.h>
#include<malloc.h>
#include<assert.h>#define ElemType int#define STACK_INIT_SIZE 8
#define STACK_INC_SIZE  3//顺序栈的定义 
typedef struct SeqStack{ElemType *base;int       capacity;int       top;    
}SeqStack;//初始化顺序栈 
void init_SeqStack(SeqStack* st){st->base = (ElemType*)malloc(sizeof(ElemType) * STACK_INIT_SIZE);st->capacity = STACK_INIT_SIZE;/*top可为 -1 [入栈:先top++在放值 出栈: 先取值在top--] 也可为 0 [入栈:先放值在++ 出栈: 先--在放值] */st->top = 0;
}//判断栈是否已满[为真返回1 为假返回0 ] 
int isFull(SeqStack* st){return st->top >= st->capacity;
}//判断栈是否为空[为真返回1 为假返回0 ]
int isEmpty(SeqStack* st){return st->top == 0;
}int inc_stack(SeqStack* st){ElemType* newBase = (ElemType*)realloc(st->base,sizeof(ElemType) * (st->capacity + STACK_INC_SIZE));if(newBase == NULL){printf("内存空间不足,无法申请空间.\n");return 0;}st->base = newBase;st->capacity += STACK_INC_SIZE;return 1;
}//入栈
void push(SeqStack* st,ElemType e){if(isFull(st) && !inc_stack(st)){printf("栈空间已满,%d 不能入栈.\n",e);return;}//如果top为-1 =>  st->base[++st->top] = e;st->base[st->top++] = e;
}//出栈
ElemType pop(SeqStack* st){if(isEmpty(st)){printf("栈空间已空,不能出栈.\n");return;} //如果top为-1 =>  return st->base[st->top--];return st->base[--st->top]; 
} //得到栈顶元素，但不出栈
ElemType get_top(SeqStack* st){if(isEmpty(st)){printf("栈空间已空,不能出栈.\n");return;} return st->base[st->top - 1];
}//栈的长度
int length(SeqStack* st){return st->top;
} //清空栈
void clear(SeqStack* st){st->top = 0;
}//销毁栈
void destroy(SeqStack* st){free(st->base);st->capacity = st->top = 0;
} //打印栈
void show_stack(SeqStack* st){int i = st->top - 1;for(i;i >= 0;i--){printf("%d\n",st->base[i]);}printf("\n");
}
int main(){SeqStack st;init_SeqStack(&st);int i = 1;for(i;i <= 5;i++){push(&st,i);}show_stack(&st);pop(&st);show_stack(&st);return 0;
} 

2、链栈

#include<stdio.h>
#include<malloc.h>
#include<assert.h>#define ElemType inttypedef struct StackNode{ElemType data;struct StackNode* next;
}StackNode;typedef StackNode* LinkStack;//注意 这里是二级指针 
void initStack(LinkStack* st){st = NULL;
}StackNode* malloc_statckNode(ElemType e){StackNode* p = (StackNode*)malloc(sizeof(StackNode));assert(p != NULL);p->data = e;p->next = NULL;
} //入栈 
void push(LinkStack* st,ElemType e){StackNode* p = malloc_statckNode(e);if(*st == NULL){//当前栈空间为空 ,新节点直接为栈顶 *st = p;} else {//新节点指向栈顶 p->next = *st;//更换栈顶 *st = p;}
} //出栈
ElemType pop(LinkStack* st) {if(*st == NULL){printf("当前栈空间为空,不可出栈.\n"); return;}StackNode* top = *st;*st = top->next;ElemType e = top->data;free(top);return e;
}
//打印栈
void show(LinkStack* st){LinkStack s = *st;while(s != NULL){printf("%d\n",s->data);s = s->next;}printf("\n");
}
int main(){LinkStack st;//二级指针接收一级指针的地址 initStack(&st);int i = 1;for(i;i <= 5;i++){push(&st,i);}show(&st);pop(&st);show(&st);return 0;
}