code/algorithm/src/main/java/com/wang/code/one/Stack.java at master · 817coder/code

72 lines (55 loc) · 1.19 KB

package com.wang.code.one;

import java.util.Iterator;

/**
 * @author WANGJJ
 * @date 2020/04/17
 */
public class Stack<T> implements Iterable<T>{

    private T[] ts;

    private int n;

    public Stack(int cap){
        ts = (T[]) new Object[cap];
    }

    public Boolean isEmpty(){
        return n == 0;
    }

    public int size(){
        return n;
    }

    public T pop(){
        T t = ts[--n];
        ts[n] = null;
        if (n > 0 && n < ts.length / 4) {
            resize(ts.length / 2);
        }
        return t;
    }

    public void push(T t){
        if (n == ts.length) {
            resize(2 * ts.length);
        }
        ts[n++] = t;
    }

    @Override
    public Iterator<T> iterator(){
        return new ReverseArrayIterator();
    }

    private void resize(int max) {
        T[] tsNew = (T[]) new Object[max];
        for (int i = 0; i < n; i++){
            tsNew[i] = ts[i];
        }
        ts = tsNew;
    }

    private class ReverseArrayIterator implements Iterator<T> {

        int i = n;

        @Override
        public boolean hasNext() {
            return i > 0;
        }

        @Override
        public T next() {
            return ts[--i];
        }
    }


}

Provide feedback

Saved searches

Use saved searches to filter your results more quickly

Expand file tree

Search code, repositories, users, issues, pull requests...

FilesExpand file tree

Stack.java

Latest commit

History

Stack.java

File metadata and controls

Expand file tree