{stack}

Data structure

1

pointer

2

linked list

3

make stack with array

5

make stack with std::stack

4

make stack with linked list

6

problems

Pointer

定義：指標變數

儲存其他變數（資料）存在的記憶起位置

1

int n

0x100

0x100

int *ptr

0x234

Type Name Value Position
int n 1 0x100
int* ptr 0x100 0x234 
int i; //int
int *ptr;//int pointer
# PRESENTING CODE

宣告

int i; //int
int *ptr;//int pointer
ptr = &i;
# PRESENTING CODE

取址(&)

int i; //int
int *ptr;//int pointer
ptr = &i;//position of i
int i; //int
int *ptr;//int pointer
ptr = &i;
# PRESENTING CODE

取值(間接運算)(*)

int i = 1; //int
int *ptr;//int pointer
ptr = &i;//position of i
int r = *ptr;//r=1
//value of the variable at ptr
*ptr = 5;//*ptr=i=5
r = 4;//r=4!=i

1

int i

0x100

0x100

int *ptr

0x234

Type Name Value Position
int i 1 0x100
int* &i 0x100 null
int* ptr 0x100 0x234
int *ptr 1(i) 0x100
int *&i 1(i) 0x100

1

int r

0x100

Independent

Linked list

null

0

null

First

curr

null

1

null

First

curr

0

Insert

prev

null

1

null

First

curr

0

Remove

prev

null

1

null

First

curr

0

Search(1)

prev

2

null

1

null

First

curr

0

Search(1)

prev

2

Array Linked list
長度 不能 可以
push O(n) O(1)
insert O(n) O(1)
remove O(n) O(1)
循序取得 O(n) O(n)
隨機取得 O(1) O(n)

Stack

定義：

Stack是一種資料結構，遵循著後進先出的原則，最晚放入堆疊的資料會被最先取出(LIFO Last-In-First-Out)

0

1

2

3

4

0

1

2

3

4

0

1

5

6

7

須製作：

  • push（新增最後一項）
  • pop（移除最後一項）
  • get（取得最後一項）
  • isEmpty（檢查是否為空）

Make Stack with Array

會遇到什麼問題：

長度無法預測，需判斷是否已滿

#include <iostream>

#define stack_length 10
using namespace std;

int stack[stack_length];
int curr = -1;

bool push(int n) {
    if (curr < stack_length - 1) {
        stack[++curr] = n;
        return true;
    }
    return false;
}

bool pop() {
    if (curr >= 0) {
        curr--;
        return true;
    }
    return false;
}

int get() {
    if (curr >= 0) {
        return stack[curr];
    }
    return -1;
}

bool isEmpty() {
    return curr == -1;
}

bool isFull() {
    return curr == stack_length - 1;
}

int main() {
    int i;
    while (cin>>i){
        switch (i) {
            case -1:
               cout<< pop()<<endl;
                break;
            case -2:
                cout<<get()<<endl;
                break;
            case -3:
                cout<<isEmpty()<<endl;
                break;
            case -4:
                cout<<isFull()<<endl;
                break;
            default:
                cout<<push(i)<<endl;
        }
    }
    return 0;
}

# PRESENTING CODE

Make Stack with Linked list

#include <iostream>

using namespace std;
struct node {
    int data;
    node *next;
};

node *curr;

void init() {
    curr = nullptr;
}

bool push(int n) {
    node *temp = curr;
    curr = new node;
    curr->next = temp;
    curr->data = n;
}

bool pop() {
    if (curr != nullptr) {
        node *temp = curr;
        curr = curr->next;
        delete temp;
        return true;
    }
    return false;
}

int get() {
    if (curr != nullptr) {
        return curr->data;
    }
    return -1;
}

bool isEmpty() {
    return curr == nullptr;
}

int main() {
    init();
    int i;
    while (cin >> i) {
        switch (i) {
            case -1:
                cout << pop() << endl;
                break;
            case -2:
                cout << get() << endl;
                break;
            case -3:
                cout << isEmpty() << endl;
                break;
            default:
                cout << push(i) << endl;
        }
    }
    return 0;
}

# PRESENTING CODE

Make Stack with std::stack

#include <iostream>
#include <stack>
using namespace std;

stack<int> s;

bool push(int n) {
    s.push(n);
}

bool pop() {
    if (!s.empty()) {
       s.pop();
        return true;
    }
    return false;
}

int get() {
    if (!s.empty()) {
        return s.top();
    }
    return -1;
}

int main() {
    int i;
    while (cin >> i) {
        switch (i) {
            case -1:
                cout << pop() << endl;
                break;
            case -2:
                cout << get() << endl;
                break;
            case -3:
                cout << s.empty() << endl;
                break;
            default:
                cout << push(i) << endl;
        }
    }
    return 0;
}

# PRESENTING CODE

Problems

c123. 00514 - Rails

c471. apcs 物品堆疊 (Stacking)

Stack

By Cheng Yan Yang

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Stack

  • 9

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