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最新推荐文章于 2018-04-04 17:51:00 发布

原创最新推荐文章于 2018-04-04 17:51:00 发布 · 875 阅读

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本文详细介绍了如何利用单个数组实现三个独立栈的数据结构。通过两种不同的方法（固定分割与灵活分割），实现每个栈的独立操作，包括堆栈的顶部元素获取、检查堆栈是否为空以及进行入栈和出栈操作。

3.1 Describe how you could use a single array to implement three stacks.

Approach 1: Fixed Division

class ThreeStack {
private:
    int stackSize;
    int *buffer;
    int stackPointer[3];
public:
    ThreeStack(int size) {
        stackSize = size;
        buffer = new int[stackSize*3];
        for (int i = 0; i < 3; i++)
            stackPointer[i] = -1;
    }
    ~ThreeStack() {
        delete[] buffer;
    }
    int absTopOfStack(int stackNum) {
        return stackNum * stackSize + stackPointer[stackNum];
    }
    bool isEmpty(int stackNum) {
        return stackPointer[stackNum] == -1;
    }
    int top(int stackNum) {
        return buffer[absTopOfStack(stackNum)];
    }
    void push(int stackNum, int value) {
        if (stackPointer[stackNum] + 1 >= stackSize) {
            throw out_of_range("Out of space.");
        }
        stackPointer[stackNum]++;
        buffer[absTopOfStack(stackNum)] = value;
    }
    int pop(int stackNum) {
        if (stackPointer[stackNum] == -1) {
            throw out_of_range("Trying to pop an empty stack.");
        }
        int value = buffer[absTopOfStack(stackNum)];
        stackPointer[stackNum]--;
        return value;
    }
};

Approach 2: Flexible Divisions