Created
August 20, 2018 09:21
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Tree Diameter problem
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import java.io.BufferedReader; | |
import java.io.InputStreamReader; | |
import java.util.ArrayList; | |
import java.util.HashMap; | |
import java.util.List; | |
import java.util.Map; | |
import java.util.stream.Collectors; | |
import java.util.stream.IntStream; | |
// Warning: Printing unwanted or ill-formatted data to output will cause the test cases to fail | |
class TestClass { | |
private final static Map<Integer, List<Integer>> map = new HashMap<>(); | |
public static void main(String args[]) throws Exception { | |
BufferedReader br = new BufferedReader(new InputStreamReader(System.in)); | |
int N = Integer.parseInt(br.readLine()); | |
for (int i = 0; i < N - 1; i++) { | |
String s = br.readLine(); | |
String[] sa = s.split("\\s"); | |
addEdge(sa[0], sa[1]); | |
} | |
IntStream.range(1, N + 1).map(in -> getMaxDistance(in)).forEach(p -> System.out.print(p + " ")); | |
} | |
private static void addEdge(String value, String to) { | |
int node = Integer.parseInt(value); | |
int toNode = Integer.parseInt(to); | |
if (map.containsKey(node)) { | |
map.get(node).add(toNode); | |
} else { | |
List<Integer> a = new ArrayList<Integer>(); | |
a.add(toNode); | |
map.put(node, a); | |
} | |
} | |
private static int getMaxDistance(int node) { | |
if (map.get(node) == null || map.get(node).size() < 1) { | |
return 0; | |
} | |
List<Integer> sortedHeight = map.get(node).stream().mapToInt(x -> height(x)).sorted().boxed() | |
.collect(Collectors.toList()); | |
if (sortedHeight.size() == 1) { | |
return 1 + sortedHeight.get(sortedHeight.size() - 1); | |
} else if (sortedHeight.size() > 1) { | |
return 2 + sortedHeight.get(sortedHeight.size() - 1) + sortedHeight.get(sortedHeight.size() - 2); | |
} | |
// | |
// List<Integer> sorted = map.get(node).stream().mapToInt(x -> | |
// getMaxDistance(x)).sorted().boxed() | |
// .collect(Collectors.toList()); | |
// | |
// if (sorted.size() == 1) { | |
// return 1 + sorted.get(sorted.size() - 1); | |
// } else if (sorted.size() > 1) { | |
// return 2 + sorted.get(sorted.size() - 1) + sorted.get(sorted.size() - 2); | |
// } | |
return 0; | |
} | |
private static int height(int node) { | |
if (map.get(node) == null || map.get(node).size() < 1) { | |
return 0; | |
} | |
return map.get(node).stream().mapToInt(x -> height(x)).max().getAsInt() + 1; | |
} | |
} |
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