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Added 2 problems to Leetcode: #34, #103 #6

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fd78f8f
Added new medium-level problem to Leetcode - Find 1st and last positi…
mohitkhosla01 Oct 7, 2019
7cdc818
Added 'BinaryTreeZigzagLevelOrderTraversal' to Leetcode
mohitkhosla01 Oct 7, 2019
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123 changes: 123 additions & 0 deletions src/com/leetcode/problems/medium/BinaryTreeZigzagLevelOrderTraversal_103.java
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Original file line number Diff line number Diff line change
@@ -0,0 +1,123 @@
package com.leetcode.problems.medium;

import java.util.ArrayList;
import java.util.List;
import java.util.Stack;

import definition.TreeNode;

/**
* @author mohitkhosla01 on 07/10/19
* Copyright (c) 2019, data-structures.
* All rights reserved.
*/
public class BinaryTreeZigzagLevelOrderTraversal_103 {

static class TreeNode {
int val;
TreeNode left;
TreeNode right;

TreeNode(int x) {
val = x;
}
}

public static void main(String[] args) {

TreeNode root = new TreeNode(3);
root.left = new TreeNode(9);
root.right = new TreeNode(20);
root.right.left = new TreeNode(15);
root.right.right = new TreeNode(7);

// TreeNode root = new TreeNode(2);
// root.left = new TreeNode(5);
// root.right = new TreeNode(20);
// root.left.left = new TreeNode(4);
// root.left.right = new TreeNode(8);
// root.right.left = new TreeNode(15);
// root.right.right = new TreeNode(12);
// root.left.left.left = new TreeNode(1);
// root.left.left.right = new TreeNode(3);
// root.left.right.left = new TreeNode(9);
// root.left.right.right = new TreeNode(7);

// TreeNode root = new TreeNode(2);

// TreeNode root = new TreeNode(5);
// root.left = new TreeNode(6);
// root.right = new TreeNode(7);
// root.left.left = new TreeNode(10);
// root.left.right = new TreeNode(3);
// root.right.left = new TreeNode(20);
// root.right.right = new TreeNode(8);
// root.left.left.left = new TreeNode(2);
// root.left.left.right = new TreeNode(9);
// root.left.right.left = new TreeNode(11);
// root.left.right.right = new TreeNode(12);
// root.right.right.left = new TreeNode(15);
// root.right.right.right = new TreeNode(16);

// TreeNode root = null;

List<List<Integer>> numLists = new BinaryTreeZigzagLevelOrderTraversal().zigzagLevelOrder(root);

for(List<Integer> numList : numLists) {
for(Integer num : numList) {
System.out.print(num + " ");
}
System.out.println();
}
}

public List<List<Integer>> zigzagLevelOrder(TreeNode root) {

List<List<Integer>> finalLists = new ArrayList<List<Integer>>();

if(root != null) {

int direction = 1;

Stack<TreeNode> currentList = new Stack<TreeNode>();
currentList.add(root);

Stack<TreeNode> nextLevelList = new Stack<TreeNode>();

List<Integer> listToBeAdded = new ArrayList<Integer>();

while(!currentList.isEmpty()) {

TreeNode node = currentList.pop();
listToBeAdded.add(node.val);

if(direction == -1) {
if(node.right != null) {
nextLevelList.add(node.right);
}
if(node.left != null) {
nextLevelList.add(node.left);
}
}
else {
if(node.left != null) {
nextLevelList.add(node.left);
}
if(node.right != null) {
nextLevelList.add(node.right);
}
}

if(currentList.isEmpty()) {
currentList = nextLevelList;
nextLevelList = new Stack<TreeNode>();
direction *= -1;
finalLists.add(listToBeAdded);
listToBeAdded = new ArrayList<Integer>();
}
}
}

return finalLists;
}
}
130 changes: 130 additions & 0 deletions src/com/leetcode/problems/medium/FindFirstAndLastPositionOfElementInSortedArray_34.java
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package com.leetcode.problems.medium;

/**
* @author mohitkhosla01 on 07/10/19
* Copyright (c) 2019, data-structures.
* All rights reserved.
*/
public class FindFirstAndLastPositionOfElementInSortedArray_34 {

public static void main(String[] args) {

int[][] nums = {
{},
null,
{1,2,3},
{1,2,3},
{1,2,3},
{1,2,3},
{5,7,7,8,8,10},
{5,7,7,8,8,8,8,8,10},
{5,8,8,8,8,8,8,8,10},
{5,7,7,8,8,10},
{1,2,3,3,3,4,5},
{1,2,3,3,3,4,5},
{1,2,3,3,3,4,5},
{1,2,3,3,4,4,4},
{1,2,3,3,3,4,4},
{1,2,3,3,3,3,4},
{1,1},
{1,2},
{1,1},
{1,2},
{1},
{2},
{2}
};

int[] target = {
1,
1,
1,
2,
3,
4,
8,
8,
8,
6,
4,
5,
1,
4,
4,
4,
1,
1,
2,
2,
1,
1,
2
};

for(int i=0; i<nums.length; ++i) {
int[] range = searchRange(nums[i], target[i]);
System.out.println(range[0] + " " + range[1]);
}
}

public static int[] searchRange(int[] nums, int target) {

int[] range = {-1, -1};

if(nums == null) {
return range;
}

int b = 0, e = nums.length - 1;
int b1 = 0, e1 = nums.length - 1;
boolean leftFound = false;

while(b <= e) {
int mid = (b + e)/2;

if(nums[mid] != target) {
if(nums[mid] > target) {
e = mid - 1;
e1 = mid - 1;
}
else {
b = mid + 1;
b1 = mid + 1;
}
}
else {
if(range[0] == -1) {
range[0] = mid;
}
if(range[1] == -1) {
range[1] = mid;
}

if(!leftFound) {
if(mid == 0 || nums[mid-1] != nums[mid]) {
leftFound = true;
range[0] = mid;
b = b1;
e = e1;
}
else {
b = b1;
e = mid;
}
}
else {
if(mid == nums.length - 1 || nums[mid+1] != nums[mid]) {
range[1] = mid;
break;
}
else {
b = mid + 1;
e = e1;
}
}
}
}

return range;
}
Comment on lines +70 to +129

@neerajjain92 neerajjain92 Oct 7, 2019

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Awesome, it would be great if you can add a recursive version of this as well.
Something like this, Optimization in this is welcome

   static int left, right;
    public static int[] searchRange(int[] nums, int target) {
        left = -1;
        right = -1;
        searchRange(nums, 0,nums.length-1, target);
        int [] result = new int[]{left, right};
        return result;  
    }
    
    private static void searchRange(int []nums, int low, int high, int target) {
        if(low <= high) {
            
            int mid = low + (high - low) / 2;
            
            if(nums[mid] < target) {
                searchRange(nums, mid+1, high, target);
            } else if (nums[mid] > target) {
                searchRange(nums, low, mid-1, target);
            } else { // Data Match
                if(mid == 0 || (left == -1 && nums[mid-1] != target)) {
                    left = mid;
                }
                if(mid == nums.length - 1 || (right == -1 && nums[mid+1] != target)) {
                    right = mid;
                }
                
                if(left == -1) {
                    searchRange(nums, low, mid-1, target);
                } 
                if(right == -1) {
                    searchRange(nums, mid+1, high, target);
                }
            }
        }
    }

}