[Leetcode][第332题][JAVA][重新安排行程][欧拉回路 / 欧拉通路][优先队列][DFS]

╰+攻爆jí腚メ 2022-12-01 12:27 205阅读 0赞

#### 【问题描述】\[中等\] ####

![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2RhZG9uZ3d1ZGk_size_16_color_FFFFFF_t_70_pic_center]

#### 【解答思路】 ####

###### 递归 ######

![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2RhZG9uZ3d1ZGk_size_16_color_FFFFFF_t_70_pic_center 1]  
![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2RhZG9uZ3d1ZGk_size_16_color_FFFFFF_t_70_pic_center 2]  
![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2RhZG9uZ3d1ZGk_size_16_color_FFFFFF_t_70_pic_center 3]

**复杂度**  
![在这里插入图片描述][20200827102458660.png_pic_center]

class Solution { 
        Map<String, PriorityQueue<String>> map = new HashMap<String, PriorityQueue<String>>();
        List<String> itinerary = new LinkedList<String>();
    
        public List<String> findItinerary(List<List<String>> tickets) { 
            for (List<String> ticket : tickets) { 
                String src = ticket.get(0), dst = ticket.get(1);
                if (!map.containsKey(src)) { 
                    map.put(src, new PriorityQueue<String>());
                }
                map.get(src).offer(dst);
            }
            dfs("JFK");
            Collections.reverse(itinerary);
            return itinerary;
        }
    
        public void dfs(String curr) { 
            while (map.containsKey(curr) && map.get(curr).size() > 0) { 
                String tmp = map.get(curr).poll();
                dfs(tmp);
            }
            itinerary.add(curr);
        }
    }

#### 【总结】 ####

###### 1. 欧拉回路 / 欧拉通路 ######

![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2RhZG9uZ3d1ZGk_size_16_color_FFFFFF_t_70_pic_center 4]

###### 2.优先队列 ######

![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2RhZG9uZ3d1ZGk_size_16_color_FFFFFF_t_70_pic_center 5]

#### 3.最大堆/最小堆初始化 ####

**最小堆**  
PriorityQueue minheap = new PriorityQueue();  
**最大堆**  
PriorityQueue maxheap = new PriorityQueue((x, y) -> y - x);  
PriorityQueue maxHeap = new PriorityQueue<>(Collections.reverseOrder());  
PriorityQueue maxHeap = new PriorityQueue(11,new Comparator()\{ //大顶堆，容量11  
@Override  
public int compare(Integer i1,Integer i2)\{  
return i2-i1;  
\}  
\});

转载链接：https://leetcode-cn.com/problems/reconstruct-itinerary/solution/zhong-xin-an-pai-xing-cheng-by-leetcode-solution/  
转载链接：https://leetcode-cn.com/problems/reconstruct-itinerary/solution/javadfsjie-fa-by-pwrliang/  
参考链接：https://www.cnblogs.com/yongh/p/9945539.html

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