前端-数据结构第一天

Applications menory

Applications menory are made by 4 component。
Heap 动态存储,我们无法再栈上控制内存的分配和释放
Stack 局部变量，还有关于函数调用的所有信息，main函数，函数里面的变量
Static/Global 全局变量区
Code(Text)

Introduction to stacks

stack ADT: A list with the restriction that insertion and deletion can be pertormed only from one end, clled the top.

• List item只能访问栈顶
• Operations: Push(x)\Pop()\Top()\IsEmpty(),constant time or O(1)
• Applications:
  • Function calls/Recursion 递归
  • undo in an editor 编辑器
  • Balanced Parentheses 算法

Implementation of stacks

1. Array implementation

//Stack - Array based implementation
#include<stion.h>
#define MAX_SIZE 101
int A[MAX_SIZE];
int top = -1;
void push(int x){
    if(top == MAX_SIZE -1){
        printf("Error: no size to push\n")
        return;
    }
    A[++top] = x;
}
void pop(){
     if(top ==  -1){
        printf("Error: no element to pop\n")
        return;
    }
    top--;
}
int Top(){
    return A[top];
}
void Print(){
    int i;
    for(i =0;i<=top;i++){
        printf("%d",A[i]);
    }
    printf("\n");
}
int main(){
    Push(2);
    Push(5);
    pop();
    Push(10);
}

doubly linked list implementation

#include<stdio.h>
#include<stdib.h>
struct Node {
    int data;
    struct Node* next;
    struct Node* prev;
}
struct Node* head;//global variable- pointer to head node.
struct Node* GetNewNode(int x){
    //local variable
    //will be cleared from menory when function call will finish.
    // struct Node myNode;
    // myNode.data = x;
    // myNode.prev = NULL;
    // myNode.next = NULL;
    //return &newNode;
    // so
    struct Node* newNode = (struct Node*)malloc(sizeof(struct Node));
    (*newNode).data = x;
    newNode->prev = NULL;
    newNode->next = NULL;
    return newNode;
}
void InsertAtHead(int x){
    struct Node* newNode = GetNewNode(x);
    if(head == NULL){
        head = newNode;
        return;
    }
    head->pre = newNode;//pre data pointer
    newNode->next = head;
    head = newNode;
}

void Print(){
      struct Node* temp = head;
      if(temp == NULL)return;//empty list,exit
    printf("Reverse:");
    while(temp!= NULL){
        printf("%d",temp->data);
        temp = temp->next;
    }
    printf("\n");
}
void ReversePrint(){
    struct Node* temp = head;
    if(temp == NULL)return;//empty list,exit
    //Going to last Node
    while(temp->next != NULL){
        temp = temp->next;
    }
    //Traversing backward using prev pointer
    printf("Reverse:");
    while(temp!= NULL){
        printf("%d",temp->data);
        temp = temp->prev;
    }
    printf("\n");
}

int main(){
    head = NULL;
InsertAtHead(2);Print();ReversePrint();
InsertAtHead(4);Print();ReversePrint();
InsertAtHead(6);Print();ReversePrint();
}