Merge pull request #2239 from Projecthappy/master

Update 0332.重新安排行程
This commit is contained in:
程序员Carl
2023-09-03 16:11:09 +08:00
committed by GitHub

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@ -345,6 +345,79 @@ class Solution {
}
```
```java
/* 该方法是对第二个方法的改进,主要变化在于将某点的所有终点变更为链表的形式,优点在于
1.添加终点时直接在对应位置添加节点避免了TreeMap增元素时的频繁调整
2.同时每次对终点进行增加删除查找时直接通过下标操作避免hashMap反复计算hash*/
class Solution {
//key为起点value是有序的终点的列表
Map<String, LinkedList<String>> ticketMap = new HashMap<>();
LinkedList<String> result = new LinkedList<>();
int total;
public List<String> findItinerary(List<List<String>> tickets) {
total = tickets.size() + 1;
//遍历tickets存入ticketMap中
for (List<String> ticket : tickets) {
addNew(ticket.get(0), ticket.get(1));
}
deal("JFK");
return result;
}
boolean deal(String currentLocation) {
result.add(currentLocation);
//机票全部用完,找到最小字符路径
if (result.size() == total) {
return true;
}
//当前位置的终点列表
LinkedList<String> targetLocations = ticketMap.get(currentLocation);
//没有从当前位置出发的机票了,说明这条路走不通
if (targetLocations != null && !targetLocations.isEmpty()) {
//终点列表中遍历到的终点
String targetLocation;
//遍历从当前位置出发的机票
for (int i = 0; i < targetLocations.size(); i++) {
targetLocation = targetLocations.get(i);
//删除终点列表中当前的终点
targetLocations.remove(i);
//递归
if (deal(targetLocation)) {
return true;
}
//路线走不通,将机票重新加回去
targetLocations.add(i, targetLocation);
result.removeLast();
}
}
return false;
}
/**
* 在map中按照字典顺序添加新元素
*
* @param start 起点
* @param end 终点
*/
void addNew(String start, String end) {
LinkedList<String> startAllEnd = ticketMap.getOrDefault(start, new LinkedList<>());
if (!startAllEnd.isEmpty()) {
for (int i = 0; i < startAllEnd.size(); i++) {
if (end.compareTo(startAllEnd.get(i)) < 0) {
startAllEnd.add(i, end);
return;
}
}
startAllEnd.add(startAllEnd.size(), end);
} else {
startAllEnd.add(end);
ticketMap.put(start, startAllEnd);
}
}
}
```
### Python
回溯 使用used数组