# Count Univalue Subtrees

Count Univalue Subtrees

Given a binary tree, count the number of uni-value subtrees.

A Uni-value subtree means all nodes of the subtree have the same value.

For example:
Given binary tree,

```              5
/ \
1   5
/ \   \
5   5   5
```

return `4`.

Solution:

```public int countUnivalSubtrees(TreeNode root) {
int[] count = new int[1];
isUnivalSubtrees(root, count);
return count[0];
}

public boolean isUnivalSubtrees(TreeNode root, int[] count) {
if (root == null) {
return false;
}
boolean left = isUnivalSubtrees(root.left, count);
boolean right = isUnivalSubtrees(root.right, count);
if (!left && !right) {
if (root.left == null && root.right == null) {
count[0]++;
return true;
}
} else if (left && right) {
if (root.left.val == root.val && root.right.val == root.val) {
count[0]++;
return true;
}
} else if (left && !right) {
if (root.right == null && root.left.val == root.val) {
count[0]++;
return true;
}
} else if (!left && right) {
if (root.left == null && root.right.val == root.val) {
count[0]++;
return true;
}
}
return false;
}```
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