ArrayDeque实际应用场景

下文笔者讲述ArrayDeque应用场景简介

1.BFS算法实现

import java.util.;

public class BFSExample {
    public void breadthFirstSearch(Graph graph, int start) {
        Deque<Integer> queue = new ArrayDeque<>();
        Set<Integer> visited = new HashSet<>();
        
        queue.offer(start);
        visited.add(start);
        
        while (!queue.isEmpty()) {
            int node = queue.poll();
            System.out.println("访问节点: " + node);
            
            // 处理相邻节点
            for (int neighbor : graph.getNeighbors(node)) {
                if (!visited.contains(neighbor)) {
                    visited.add(neighbor);
                    queue.offer(neighbor);
                }
            }
        }
    }
}

2.滑动窗口最大值

public class SlidingWindowMaximum {
    public int[] maxSlidingWindow(int[] nums, int k) {
        if (nums == null || nums.length == 0) return new int[0];
        
        Deque<Integer> deque = new ArrayDeque<>(); // 存储索引
        int[] result = new int[nums.length - k + 1];
        
        for (int i = 0; i < nums.length; i++) {
            // 移除超出窗口范围的元素
            while (!deque.isEmpty() && deque.peekFirst() < i - k + 1) {
                deque.pollFirst();
            }
            
            // 维护单调递减队列
            while (!deque.isEmpty() && nums[deque.peekLast()] < nums[i]) {
                deque.pollLast();
            }
            
            deque.offerLast(i);
            
            // 记录窗口最大值
            if (i >= k - 1) {
                result[i - k + 1] = nums[deque.peekFirst()];
            }
        }
        
        return result;
    }
}

3.表达式求值

public class ExpressionEvaluation {
    public int evaluateExpression(String expression) {
        Deque<Integer> values = new ArrayDeque<>();
        Deque<Character> operators = new ArrayDeque<>();
        
        // 简化的中缀表达式求值逻辑
        // 使用两个栈分别存储操作数和操作符
        
        return values.peek();
    }
}