标签:操作 leetcode == could turn str push operation ati
小结:
1、
常数时间内检索到最小元素
最小栈 - 力扣(LeetCode)
https://leetcode-cn.com/problems/min-stack/
设计一个支持 push,pop,top 操作,并能在常数时间内检索到最小元素的栈。
示例:
MinStack minStack = new MinStack(); minStack.push(-2); minStack.push(0); minStack.push(-3); minStack.getMin(); --> 返回 -3. minStack.pop(); minStack.top(); --> 返回 0. minStack.getMin(); --> 返回 -2.
package leetcode;
import java.util.Stack;
class MinStack {
int min = Integer.MAX_VALUE;
Stack<Integer> stack = new Stack<Integer>();
public static void main(String[] args) {
MinStack minStack = new MinStack();
minStack.push(-2);
minStack.push(0);
minStack.push(-3);
minStack.getMin();
minStack.pop();
minStack.top();
minStack.getMin();
}
public void push(int x) {
// only push the old minimum value when the current
// minimum value changes after pushing the new value x
if (x <= min) {
stack.push(min);
min = x;
}
stack.push(x);
}
public void pop() {
// if pop operation could result in the changing of the current minimum value,
// pop twice and change the current minimum value to the last minimum value.
if (stack.pop() == min) min = stack.pop();
}
public int top() {
return stack.peek();
}
public int getMin() {
return min;
}
}
(3) Clean 6ms Java solution - LeetCode Discuss
https://leetcode.com/problems/min-stack/discuss/49010/Clean-6ms-Java-solution
不借助java stack
package leetcode;
class MinStack {
private Node head;
public void push(int x) {
if (head == null)
head = new Node(x, x);
else
head = new Node(x, Math.min(x, head.min), head);
}
public void pop() {
head = head.next;
}
public int top() {
return head.val;
}
public int getMin() {
return head.min;
}
private class Node {
int val;
int min;
Node next;
private Node(int val, int min) {
this(val, min, null);
}
private Node(int val, int min, Node next) {
this.val = val;
this.min = min;
this.next = next;
}
}
}
设计一个支持 push,pop,top 操作,并能在常数时间内检索到最小元素的栈
标签:操作 leetcode == could turn str push operation ati
原文地址:https://www.cnblogs.com/yuanjiangw/p/10801228.html