class Solution {
public int countPrimes(int n) {
int count = 0;
for (int i = 2; i < n; i++){
if (isPrime(i)) count++;
}
return count;
}
public boolean isPrime(int n){
for (int i = 2; i*i <= n; i++){
if ( n % i == 0) return false;
}
return true;
}
}
637. Average of Levels in Binary Tree
/**
* Definition for a binary tree node.
* public class TreeNode {
* int val;
* TreeNode left;
* TreeNode right;
* TreeNode(int x) { val = x; }
* }
*/
class Solution {
public List averageOfLevels(TreeNode root) {
List out = new ArrayList();
Queue q = new LinkedList();
q.add(root);
while(! q.isEmpty()){
int len = q.size();
Double sum = 0.0;
for (int i = 0; i < len; i++){
TreeNode c = q.remove();
if (c != null){
sum += c.val;
if(c.left !=null)q.add(c.left);
if(c.right != null)q.add(c.right);
}
}
out.add(sum/len);
}
return out;
}
}
class Solution {
public int binaryGap(int N) {
String binary = Integer.toBinaryString(N);
int first = 0;
while (first < binary.length() && binary.charAt(first) != '1'){
first ++;}
if (first == binary.length()) return 0;
int diff = Integer.MIN_VALUE;
int current = first;
for (int i = first+1; i diff){
diff = i - current;
}
current = i;
}
}
if (diff == Integer.MIN_VALUE) return 0;
return diff;
}
}
884. Uncommon Words from Two Sentences
class Solution {
public String[] uncommonFromSentences(String A, String B) {
List outputList = new ArrayList();
String[] As = A.split(" ");
String[] Bs = B.split(" ");
Map s = new HashMap();
for (int i = 0; i < As.length; i++){
if(s.get(As[i]) == null) s.put(As[i],1);
else s.put(As[i],s.get(As[i])+1);
}
for (int i = 0; i < Bs.length; i++){
if(s.get(Bs[i]) == null) s.put(Bs[i],1);
else s.put(Bs[i],s.get(Bs[i])+1);
}
for (String a: s.keySet()){
if ( s.get (a) == 1) outputList.add(a);
}
return outputList.toArray(new String[outputList.size()]);
}
}
/**
* Definition for a binary tree node.
* public class TreeNode {
* int val;
* TreeNode left;
* TreeNode right;
* TreeNode(int x) { val = x; }
* }
*/
class Solution {
public int rangeSumBST(TreeNode root, int L, int R) {
int out = 0;
out = rangeSumBSTHelper(root,L,R);
return out;
}
public static int rangeSumBSTHelper(TreeNode root, int L, int R){
if(root == null) return 0;
int total = 0;
if( root.val >= L && root.val <= R)
total+= root.val;
if (root.right != null)
total+= rangeSumBSTHelper(root.right,L,R);
if (root.left != null)
total+=rangeSumBSTHelper(root.left,L,R);
return total;
}
}
/**
* Definition for a binary tree node.
* public class TreeNode {
* int val;
* TreeNode left;
* TreeNode right;
* TreeNode(int x) { val = x; }
* }
*/
class Solution {
public boolean leafSimilar(TreeNode root1, TreeNode root2) {
ArrayList tree1 = new ArrayList();
ArrayList tree2 = new ArrayList();
traverse(root1, tree1);
traverse(root2, tree2);
if (tree1.size() != tree2.size()) return false;
for (int i = 0; i < tree1.size(); i++){
if (tree1.get(i) != tree2.get(i)) return false;
}
return true;
}
public static void traverse (TreeNode root, ArrayList tree){
if( root.right == null && root.left == null){
tree.add(root.val);
return;
}
if (root.right != null) traverse (root.right, tree);
if (root.left != null) traverse (root.left, tree);
}
}
Go to a video from this channel
click on channel name
Copy the string UC************** that is in the end of channel URL https://www.youtube.com/channel/UC**************
replace UC************** with UU**************
Run any video from this channel and add to its url: &list=UU**************
Reference:
