Ch3-3: popat(int idx) of setofstack_class stack|int idx=0-优快云博客

本文链接：https://blog.youkuaiyun.com/asicprogrammer/article/details/18300211

本文探讨了使用类设计解决方案并引入STL容器（如vector, stack, set等）来优化堆栈集合类的实现。通过避免直接使用pop方法，并详细解释了在set of stacks类中设计弹出操作时遇到的边界条件问题，特别是当中间存在空子堆时，需要使用while循环而非if条件。提供了一个改进的SetOfStacks1类，展示了如何更精确地处理堆栈的空状态和满状态，同时保持代码的简洁性和专业性。

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Continue to use class to design solution, also, start to use STL, such as container (vector, stack, set, ...). save time and to be more professional.

The design without popat method is similar to the one to devide a single array into 3 stacks.

But the class of setofstack with popat should be more carefully.

for example:

bool empty(){  // empty of the whole set
		//if(cur==0) return st[cur].empty();
            // this is not working because it might have 
            // blank substack in the middle of full stack
            // so need to have while condition to find the last 
            // not-empty stack
        // if (cur!=-1 && st[cur].empty()) --cur; --->
            // this one only find the previous stack of 
            // empty stack, need to use while condition instead
		while(cur!=-1 && st[cur].empty()) --cur;
		if (cur==-1) return true;
		return false;
	}

Full code. Still, this is modified from Hawstein's code but may not the best solution, learn from others too..

// solution to Ch 3-3
// Ch3-3: popAt(int idx) should be careful in designing the 
// corner conditions, such as the empty method of setofstack
// (with popat, due to the condition of empty substack in 
// middle, need to use while condition instead of if condition)
//

#include 
using namespace std;

const int STACK_SIZE = 10;
const int STACK_NUM = 5;

class stack{
public:
    stack(int size=STACK_SIZE){
        buf = new int[size];
		ptop = -1;
		this->capacity = size;
	}

	~stack(){
		delete[] buf;
	}

	void push(int val){
		buf[++ptop] = val;
        //cout << "push" << endl;
	}

	void pop(){
		--ptop;
        //cout << "pop" << endl;
	}

	int top(){
		return buf[ptop];
        cout << "T" << endl;
	}

	bool empty(){
		return ptop==-1;
        cout << "E" << endl;
	}

	bool full(){
		return ptop==capacity-1;
	    cout << "F" << endl;
    }

private:
	int* buf;
	int ptop;
	int capacity;
};

class SetOfStacks{//without popAt()
public:
	SetOfStacks(int size = STACK_NUM){
		st = new stack[size];
		cur = 0;
		this->capacity = size;
	}	

	~SetOfStacks(){
		delete[] st;
	}

	void push(int val){
		if(st[cur].full()) ++cur;
		st[cur].push(val);
	}

	void pop(){
		if(st[cur].empty()) --cur;
		st[cur].pop();
	}

	int top(){
		if(st[cur].empty()) --cur;
		return st[cur].top();
	}

	bool empty(){  // empty of the whole set
		if(cur==0) return st[cur].empty();
		return false;
	}

	bool full(){
		if(cur==capacity-1) return st[cur].full();
		return false;
	}

private:
	stack *st;
	int cur;
	int capacity;
};

class SetOfStacks1{//with popAt()
public:
	SetOfStacks1(int size = STACK_NUM){
		st = new stack[size];
		cur = 0;
		this->capacity = size;
	}	

	~SetOfStacks1(){
		delete[] st;
	}

	void push(int val){
		if(st[cur].full()) ++cur;
		st[cur].push(val);
	}

	void pop(){
		while(st[cur].empty()) --cur;
		st[cur].pop();
	}
/*
	void popAt(int idx){ // should not pop if that stack is empty
		if(~st[idx].empty()) cout << "no popat" <
            // this one only find the previous stack of 
            // empty stack, need to use while condition instead
		while(cur!=-1 && st[cur].empty()) --cur;
		if (cur==-1) return true;
		return false;
	}

	bool full(){
		if(cur==capacity-1) return st[cur].full();
		return false;
	}

private:
	stack *st;
	int cur;
	int capacity;
};

int main(){
#if 0
     SetOfStacks ss0;
     for(int i=0; i




output:

Executing the program....
$demo 
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huxiaolin ...TOT