package stack;
import java.util.ArrayList;
/**
* 实现包含min函数的栈
* @author DHC
* @param
*/
public class MinInStack {
public static void main(String[] args) {
MinInStack newStack = new MinInStack();
newStack.push(4);
newStack.push(6);
newStack.push(2);
newStack.push(5);
newStack.pop();
newStack.pop();
newStack.push(1);
System.out.println(newStack.min());
}
public ArrayList stack = new ArrayList();
public ArrayList minStack = new ArrayList();
public T pop() {
int size = stack.size();
minStack.remove(size - 1);
return stack.remove(size - 1);
}
public void push(T item) {
int size = stack.size();
if (size == 0) {
minStack.add(0);
} else {
int minPosition = minStack.get(size - 1);
T minData = stack.get(minPosition);
if (compare(minData, item)) {
minStack.add(stack.size());
} else {
minStack.add(minPosition);
}
}
stack.add(item);
}
public T peek() {
int size = stack.size();
return stack.get(size - 1);
}
public T min() {
int size = minStack.size();
return stack.get(minStack.get(size - 1));
}
public boolean isEmpty() {
return stack.isEmpty();
}
/**
* 泛型元素的比较方法
* @param minData
* @param item
* @return true 代表当前元素小于之前的最小元素
*/
private boolean compare(T minData, T item) {
// 这儿不同的泛型类型可以用不同的方式实现
// 如果写成通用代码泛型之间应该肿么比较大小呢？是不是可以让泛型都继承某一接口呢？
int a = (Integer) minData;
int b = (Integer) item;
if(a > b) {
return true;
} else {
return false;
}
}
}
posted on 2012-01-31 15:57 墙头草 阅读(982) 评论(0) 编辑 收藏
