Leetcode232（用栈实现队列）
package stack_queue;import java.util.Stack;public class Leetcode232 {public static void main(String[] args) {MyQueue myQueue = new MyQueue();myQueue.push(1);myQueue.push(2);System.out.print(myQueue.peek());System.out.print(myQueue.peek());System.out.print(myQueue.isEmpty());}}
class MyQueue{Stack<Integer> stackIn;Stack<Integer> stackOut;//初始化public MyQueue() {this.stackIn = new Stack<>();this.stackOut = new Stack<>();}public void push(int x) {stackIn.push(x);}public boolean isEmpty() {return stackIn.empty()&&stackOut.empty();}public int pop() {dumpStackIn();return stackOut.pop();}public int peek() {dumpStackIn();return stackOut.peek();}private void dumpStackIn() {if(!stackOut.empty())return; //如果出栈不为空则什么都不做while(!stackIn.empty()) {stackOut.push(stackIn.pop());}}
}
Leetcode235（队列实现栈）
package stack_queue;import java.util.LinkedList;
import java.util.Queue;public class Leetcode235 {public static void main(String[] agrs) {Stack02 stack = new Stack02();stack.push(1);stack.push(2);stack.pop();stack.push(3);stack.push(4);stack.pop();System.out.print(stack.peek());}}
//单队列实现栈
class Stack02{Queue<Integer> queue;public Stack02() {this.queue = new LinkedList<>();}public boolean isEmpty() {return queue.isEmpty();}public void push(int x) {queue.offer(x);int size = queue.size();size--;while(size-->0) {queue.offer(queue.poll());}}public void pop() {queue.poll();}public int peek() {return queue.peek();}
}//双队列实现栈
class Stack{Queue<Integer> queue1;Queue<Integer> queue2;public Stack() {this.queue1 = new LinkedList<>();this.queue2 = new LinkedList<>();}public void push(int x) {queue2.offer(x);while(!queue1.isEmpty()) {queue2.offer(queue1.poll());}Queue<Integer> queueTemp;queueTemp = queue1;queue1 = queue2;queue2 = queueTemp;}public int pop() {return queue1.poll();}public int top() {return queue1.peek();}public boolean empty() {return queue1.isEmpty();}
}
Leetcode20（有效括号）
package stack_queue;
import java.util.Stack;public class Leetcode20 {public static void main(String[] args) {System.out.print(matchWay("("));}public static boolean matchWay(String str) {Stack<Character> stack = new Stack<>();for(int i =0;i<str.length();i++) {char ch = str.charAt(i);if(ch =='(') {stack.push(')');}else if(ch == '[') {stack.push(']');}else if(ch == '{') {stack.push('}');}else if(stack.empty()||ch!=stack.peek()) {return false;}else {stack.pop();}}return stack.empty();}
}
Leetcode1047（删除字符串中的所有相邻重复项）
package stack_queue;
import java.util.Stack;public class Leetcode1047 {public static void main(String[] args) {System.out.print(match("aacbbcca"));}//stack方法public static String match(String str) {Stack<Character> stack = new Stack();for(int i =0;i<str.length();i++) {char chars = str.charAt(i);if(stack.empty()||stack.peek()!=chars) {stack.push(chars);}else {stack.pop();}}String str02 = " ";while(!stack.empty()) {str02 = stack.pop()+str02;}return str02;}//字符串作栈public static String match02(String str) {StringBuilder strBulider = new StringBuilder();int top = -1;for(int i=0;i<str.length();i++) {char c = s.charAt(i);if(top>=0&&strBulider.charAt(top)==c) {strBulider.deleteCharAt(top);top--;}else {strBulider.append(c);top++;}}return strBulider.toString();}}
)
