riyafa

class ArrangingCoinsBS {
    public int arrangeCoins(int n) {
        int low = 1; 
        int high = n;
        while(low < high) {
            int mid = low +(high -low+1)/2;
            long num = (((long)mid * ((long)mid +1l))/2l);
            if(num == n) {
                return mid;
            } else if(n < num){

riyafa

class RomanToInteger {
    public int romanToInt(String s) {
        int prev = 0;
        int result = 0;
        for(int i = s.length() -1; i >= 0; i--) {
            char cur = s.charAt(i);
            int curVal = getInteger(cur);
            if(curVal < prev) {
                result -= curVal;
            } else {

riyafa

class MinimumDepthBinaryTreeDFS {
    public int minDepth(TreeNode root) {
        if(root == null) {
            return 0;
        }
        int leftHeight = minDepth(root.left);
        int rightHeight = minDepth(root.right);
        if(leftHeight == 0 || rightHeight == 0) {
            return leftHeight + rightHeight + 1;
        }

riyafa

class MinimumDepthBinaryTreeBFS {
    public int minDepth(TreeNode root) {
        if(root == null) {
            return 0;
        }
        Queue<TreeNode> queue = new LinkedList<>();
        queue.add(root);
        int level = 0;
        while(!queue.isEmpty()) {
            level++;

riyafa

Hello World!