_1457.java

packagecom.fishercoder.solutions.secondthousand;

importcom.fishercoder.common.classes.TreeNode;
importjava.util.ArrayList;
importjava.util.HashMap;
importjava.util.List;
importjava.util.Map;

publicclass_1457 {
publicstaticclassSolution1 {
publicintpseudoPalindromicPaths(TreeNoderoot) {
List<List<Integer>> allPaths = newArrayList<>();
List<Integer> path = newArrayList<>();
dfs(root, path, allPaths);
intresult = 0;
for (List<Integer> thisPath : allPaths) {
Map<Integer, Integer> count = findCount(thisPath);
intoddCount = 0;
for (intnum : count.keySet()) {
if (count.get(num) % 2 != 0) {
oddCount++;
 }
if (oddCount > 1) {
break;
 }
 }
if (oddCount <= 1) {
result++;
 }
 }
returnresult;
 }

privatevoiddfs(TreeNoderoot, List<Integer> path, List<List<Integer>> allPaths) {
if (root.left == null && root.right == null) {
path.add(root.val);
allPaths.add(newArrayList<>(path));
return;
 }
path.add(root.val);
if (root.left != null) {
dfs(root.left, path, allPaths);
path.remove(path.size() - 1);
 }
if (root.right != null) {
dfs(root.right, path, allPaths);
path.remove(path.size() - 1);
 }
 }

privateMap<Integer, Integer> findCount(List<Integer> path) {
Map<Integer, Integer> map = newHashMap<>();
path.forEach(i -> map.put(i, map.getOrDefault(i, 0) + 1));
returnmap;
 }
 }
}