LeetCode 1257: Smallest Common Region Solution
Master LeetCode problem 1257 (Smallest Common Region), a medium challenge, with our optimized solutions in Java, C++, and Python. Explore detailed explanations, test your code in our interactive editor, and prepare for coding interviews.
1257. Smallest Common Region
Problem Explanation
Explanation:
To find the smallest common region between two given regions in a hierarchy, we can follow these steps:
- Build a map to store the parent-child relationships for each region.
- Find the path from the given regions to the root.
- Compare the two paths to find the smallest common region.
Time complexity: O(n) where n is the number of regions Space complexity: O(n) for storing the parent-child relationships
Solution Code
import java.util.*;
class Solution {
public String findSmallestRegion(List<List<String>> regions, String region1, String region2) {
Map<String, String> parent = new HashMap<>();
for (List<String> region : regions) {
String par = region.get(0);
for (int i = 1; i < region.size(); i++) {
parent.put(region.get(i), par);
}
}
Set<String> path1 = new HashSet<>();
String curr = region1;
while (curr != null) {
path1.add(curr);
curr = parent.get(curr);
}
curr = region2;
while (curr != null) {
if (path1.contains(curr)) {
return curr;
}
curr = parent.get(curr);
}
return null;
}
}Try It Yourself
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