More solutions

omprashantjain · omprashantjain · commit db15f3cb073a · 2024-04-28T11:48:54.000+05:30
diff --git a/1 Leetcode Easy Problems/Leetcode 141 Linked List Cycle.java b/1 Leetcode Easy Problems/Leetcode 141 Linked List Cycle.java
@@ -0,0 +1,33 @@
+/**
+ * Definition for singly-linked list.
+ * class ListNode {
+ * int val;
+ * ListNode next;
+ * ListNode(int x) {
+ * val = x;
+ * next = null;
+ * }
+ * }
+ */
+class Solution {
+  public boolean hasCycle(ListNode head) {
+    if (head == null || head.next == null) {
+      return false;
+    }
+    ListNode first = head;
+    ListNode second = first.next;
+    while (second != null && first != null) {
+      if (first == second) {
+        return true;
+      }
+      second = second.next != null ? second.next.next : null;
+      first = first.next;
+    }
+    return false;
+  }
+}
+
+
+
+
+
diff --git a/1 Leetcode Easy Problems/Leetcode 160 Intersection of Two Linked Lists.java b/1 Leetcode Easy Problems/Leetcode 160 Intersection of Two Linked Lists.java
@@ -0,0 +1,27 @@
+/**
+ * Definition for singly-linked list.
+ * public class ListNode {
+ * int val;
+ * ListNode next;
+ * ListNode(int x) {
+ * val = x;
+ * next = null;
+ * }
+ * }
+ */
+class Solution {
+  public ListNode getIntersectionNode(ListNode headA, ListNode headB) {
+    if (headA == headB)
+      return headA;
+    if (headA == null || headB == null)
+      return null;
+
+    ListNode first = headA;
+    ListNode second = headB;
+    while (first != second) {
+      first = first != null ? first.next : headB;
+      second = second != null ? second.next : headA;
+    }
+    return first;
+  }
+}
diff --git a/1 Leetcode Easy Problems/Leetcode 190 Reverse Bits.java b/1 Leetcode Easy Problems/Leetcode 190 Reverse Bits.java
@@ -0,0 +1,12 @@
+class Solution {
+  // you need treat n as an unsigned value
+  public int reverseBits(int n) {
+    int result = 0;
+    for (int i = 0 ; i < 32; i++) {
+      result = result << 1;
+      result = result | (n & 1);
+      n = n >>> 1;
+    }
+    return result;
+  }
+}
diff --git a/1 Leetcode Easy Problems/Leetcode 191 Number of 1 Bits.java b/1 Leetcode Easy Problems/Leetcode 191 Number of 1 Bits.java
@@ -0,0 +1,12 @@
+class Solution {
+  public int hammingWeight(int n) {
+    int count = 0;
+    while (n > 0) {
+      if ((n & 1) == 1) {
+        count++;
+      }
+      n >>= 1;
+    }
+    return count;
+  }
+}
diff --git a/1 Leetcode Easy Problems/Leetcode 202 Happy Number.java b/1 Leetcode Easy Problems/Leetcode 202 Happy Number.java
@@ -0,0 +1,25 @@
+import java.util.*;
+
+class Solution {
+  public boolean isHappy(int n) {
+    Set<Integer> set = new HashSet<>();
+    while (n != 1) {
+      if (set.contains(n)) {
+        return false;
+      }
+      set.add(n);
+      n = sumOfSquareOfDigits(n);
+    }
+    return true;
+  }
+
+  private int sumOfSquareOfDigits(int num) {
+    int result = 0;
+    while (num > 0) {
+      int rem = num % 10;
+      result += rem * rem;
+      num /= 10;
+    }
+    return result;
+  }
+}
diff --git a/1 Leetcode Easy Problems/Leetcode 203 Remove Linked List Elements.java b/1 Leetcode Easy Problems/Leetcode 203 Remove Linked List Elements.java
@@ -0,0 +1,38 @@
+/**
+ * Definition for singly-linked list.
+ * public class ListNode {
+ * int val;
+ * ListNode next;
+ * ListNode() {}
+ * ListNode(int val) { this.val = val; }
+ * ListNode(int val, ListNode next) { this.val = val; this.next = next; }
+ * }
+ */
+class Solution {
+  public ListNode removeElements(ListNode head, int val) {
+    ListNode dummy = new ListNode();
+    dummy.next = head;
+
+    ListNode temp = dummy;
+    while (temp.next != null) {
+      if (temp.next.val == val) {
+        temp.next = temp.next.next;
+      } else {
+        temp = temp.next;
+      }
+    }
+    return dummy.next;
+  }
+}
+
+
+
+
+
+
+
+
+
+
+
+
diff --git a/1 Leetcode Easy Problems/Leetcode 206 Reverse Linked List.java b/1 Leetcode Easy Problems/Leetcode 206 Reverse Linked List.java
@@ -0,0 +1,25 @@
+/**
+ * Definition for singly-linked list.
+ * public class ListNode {
+ * int val;
+ * ListNode next;
+ * ListNode() {}
+ * ListNode(int val) { this.val = val; }
+ * ListNode(int val, ListNode next) { this.val = val; this.next = next; }
+ * }
+ */
+class Solution {
+  public ListNode reverseList(ListNode head) {
+    ListNode prev = null;
+    ListNode current = head;
+
+    while (current != null) {
+      ListNode temp = current.next;
+      current.next = prev;
+      prev = current;
+      current = temp;
+    }
+    
+    return prev;
+  }
+}
diff --git a/1 Leetcode Easy Problems/Leetcode 222 Count Complete Tree Nodes.java b/1 Leetcode Easy Problems/Leetcode 222 Count Complete Tree Nodes.java
@@ -0,0 +1,22 @@
+/**
+ * Definition for a binary tree node.
+ * public class TreeNode {
+ * int val;
+ * TreeNode left;
+ * TreeNode right;
+ * TreeNode() {}
+ * TreeNode(int val) { this.val = val; }
+ * TreeNode(int val, TreeNode left, TreeNode right) {
+ * this.val = val;
+ * this.left = left;
+ * this.right = right;
+ * }
+ * }
+ */
+class Solution {
+  public int countNodes(TreeNode root) {
+    if (root == null) return 0;
+    return 1 + countNodes(root.left) 
+             + countNodes(root.right);
+  }
+}
