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Copy pathBfsProblems.java
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125 lines (108 loc) · 4.03 KB
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import java.util.*;
class BfsProblems {
public static void main(String[] args) {
Node root = new Node(1);
root.left = new Node(2);
root.right = new Node(3);
root.left.right = new Node(4);
root.right.left = new Node(5);
root.right.right = new Node(6);
root.right.left.left = new Node(7);
root.right.left.right = new Node(8);
// findAllRightNodes(root);
// System.out.println("Min Depth Value is = " + findMinDepth(root));
// printTree(root);
printNodes(root);
}
private static void printTree(Node node) {
HashMap<Integer, ArrayList<Integer>> treeMap = new HashMap<>();
mapTreeLevels(node, treeMap, 1);
LinkedList<List<Integer>> reverseLevel = new LinkedList<>();
// Top to Bottom
treeMap.forEach((level, nodeValues) -> {
System.out.print(treeMap.get(level));
reverseLevel.addFirst(treeMap.get(level));
});
System.out.println();
// Bottom To Top
reverseLevel.forEach(System.out::print);
}
public static void insertIntoMultiMap(Map<Integer, List<Integer>> map,
Integer key, Integer value) {
map.putIfAbsent(key, new ArrayList<>());
map.get(key).add(value);
}
public static void printNodes(Node node) {
if (node == null) return;
int level = 1;
Map<Integer, List<Integer>> map = new HashMap<>();
insertIntoMultiMap(map, level, node.getData());
Queue<Node> q1 = new ArrayDeque<>(), q2 = new ArrayDeque<>();
if (node.left != null && node.right != null) {
q1.add(node.left);
q2.add(node.right);
}
while (!q1.isEmpty()) {
level++;
int n = q1.size();
while (n-- > 0) {
Node x = q1.poll();
if (x != null) {
insertIntoMultiMap(map, level, x.getData());
if (x.left != null) q1.add(x.left);
if (x.right != null) q1.add(x.right);
}
Node y = q2.poll();
if (y != null) {
map.get(level).add(y.getData());
if (y.right != null) q2.add(y.right);
if (y.left != null) q2.add(y.left);
}
}
}
for (int i = map.size(); i > 0; i--) {
System.out.print(map.get(i));
}
}
private static void mapTreeLevels(Node node, HashMap<Integer, ArrayList<Integer>> treeMap, int level) {
if (node == null) return;
ArrayList<Integer> nodes = new ArrayList<>();
if (treeMap.containsKey(level)) nodes = treeMap.get(level);
nodes.add(node.getData());
treeMap.put(level, nodes);
mapTreeLevels(node.left, treeMap, level + 1);
mapTreeLevels(node.right, treeMap, level + 1);
}
private static int findMinDepth(Node node) {
if (node == null) return 0;
int l = findMinDepth(node.left);
int r = findMinDepth(node.right);
if (node.left == null) return r + 1;
if (node.right == null) return l + 1;
return Math.min(l, r) + 1;
}
private static void findAllRightNodes(Node root) {
Map<Integer, Integer> rightNodes = new HashMap<>();
printAllRightNodes(rightNodes, 1, root);
rightNodes.values().forEach(System.out::print);
}
private static void printAllRightNodes(Map<Integer, Integer> rightNodes, int level, Node root) {
if (root == null) return;
// Add this condition to get left view of tree:
// if (!rightNodes.containsKey(level))
rightNodes.put(level, root.getData());
printAllRightNodes(rightNodes, level + 1, root.left);
printAllRightNodes(rightNodes, level + 1, root.right);
}
}
class Node {
private final int data;
Node left, right;
Node(int data) {
this.data = data;
this.left = this.right = null;
}
public int getData() {
return this.data;
}
}