Added more solutions to all categories

kanahaiya · kanahaiya · commit bfee36b972fc · 2018-03-08T00:57:21.000+05:30
diff --git a/LeetCodeSolutions/EasyLevelSolutions/src/main/java/com/javaaid/solutions/easy/bitmanipulations/CountingBits.java b/LeetCodeSolutions/EasyLevelSolutions/src/main/java/com/javaaid/solutions/easy/bitmanipulations/CountingBits.java
@@ -0,0 +1,18 @@
+/**
+ * 
+ */
+package com.javaaid.solutions.easy.bitmanipulations;
+
+/**
+ * @author Kanahaiya Gupta
+ *
+ */
+public class CountingBits {
+	public int[] countBits(int num) {
+        int dp[]=new int[num+1];
+        for(int i=0;i<=num;i++){
+            dp[i]=dp[i>>1]+(i&1);
+        }
+        return dp;
+    }
+}
diff --git a/LeetCodeSolutions/EasyLevelSolutions/src/main/java/com/javaaid/solutions/easy/bitmanipulations/NumberOf1Bits.java b/LeetCodeSolutions/EasyLevelSolutions/src/main/java/com/javaaid/solutions/easy/bitmanipulations/NumberOf1Bits.java
@@ -0,0 +1,19 @@
+/**
+ * 
+ */
+package com.javaaid.solutions.easy.bitmanipulations;
+
+/**
+ * @author Kanahaiya Gupta
+ *
+ */
+public class NumberOf1Bits {
+	 public int hammingWeight(int n) {
+	        int noOfOnes=0;
+	        while(n!=0){
+	            n=n&(n-1);
+	            noOfOnes++;
+	        }
+	        return noOfOnes;
+	    }
+}
diff --git a/LeetCodeSolutions/EasyLevelSolutions/src/main/java/com/javaaid/solutions/easy/bitmanipulations/PowerOfFour.java b/LeetCodeSolutions/EasyLevelSolutions/src/main/java/com/javaaid/solutions/easy/bitmanipulations/PowerOfFour.java
@@ -0,0 +1,14 @@
+/**
+ * 
+ */
+package com.javaaid.solutions.easy.bitmanipulations;
+
+/**
+ * @author Kanahaiya Gupta
+ *
+ */
+public class PowerOfFour {
+	public boolean isPowerOfFour(int num) {
+        return (num>0 && (num&(num-1))==0 && (num&0x55555555)!=0);
+    }
+}
diff --git a/LeetCodeSolutions/EasyLevelSolutions/src/main/java/com/javaaid/solutions/easy/bitmanipulations/PowerOfTwo.java b/LeetCodeSolutions/EasyLevelSolutions/src/main/java/com/javaaid/solutions/easy/bitmanipulations/PowerOfTwo.java
@@ -0,0 +1,14 @@
+/**
+ * 
+ */
+package com.javaaid.solutions.easy.bitmanipulations;
+
+/**
+ * @author Kanahaiya Gupta
+ *
+ */
+public class PowerOfTwo {
+	public boolean isPowerOfTwo(int n) {
+        return (n>0 && (n&(n-1))==0);
+    }
+}
diff --git a/LeetCodeSolutions/EasyLevelSolutions/src/main/java/com/javaaid/solutions/easy/dp/MinCostClimbingStairs.java b/LeetCodeSolutions/EasyLevelSolutions/src/main/java/com/javaaid/solutions/easy/dp/MinCostClimbingStairs.java
@@ -8,14 +8,14 @@
  *
  */
 public class MinCostClimbingStairs {
-public int minCostClimbingStairs(int[] cost) {
-	int n=cost.length;
-     int[] dp=new int[cost.length+1];
-     dp[0]=cost[0];
-     dp[1]=cost[1];
-	for(int i=2;i<cost.length;i++) {
-		dp[i]=cost[i]+Math.min(dp[i-1], dp[i-2]);
+	public int minCostClimbingStairs(int[] cost) {
+		int n = cost.length;
+		int[] dp = new int[cost.length + 1];
+		dp[0] = cost[0];
+		dp[1] = cost[1];
+		for (int i = 2; i < cost.length; i++) {
+			dp[i] = cost[i] + Math.min(dp[i - 1], dp[i - 2]);
+		}
+		return Math.min(dp[n - 2], dp[n - 1]);
 	}
-	return Math.min(dp[n-2], dp[n-1]);
-    }
 }
diff --git a/LeetCodeSolutions/EasyLevelSolutions/src/main/java/com/javaaid/solutions/easy/strings/ReverseString.java b/LeetCodeSolutions/EasyLevelSolutions/src/main/java/com/javaaid/solutions/easy/strings/ReverseString.java
@@ -0,0 +1,18 @@
+/**
+ * 
+ */
+package com.javaaid.solutions.easy.strings;
+
+/**
+ * @author Kanahaiya Gupta
+ *
+ */
+public class ReverseString {
+	public String reverseString(String s) {
+		StringBuilder sb = new StringBuilder();
+		for (int i = s.length() - 1; i >= 0; i--) {
+			sb.append(s.charAt(i));
+		}
+		return sb.toString();
+	}
+}
diff --git a/LeetCodeSolutions/EasyLevelSolutions/src/main/java/com/javaaid/solutions/easy/trees/MaximumDepthOfBinaryTree.java b/LeetCodeSolutions/EasyLevelSolutions/src/main/java/com/javaaid/solutions/easy/trees/MaximumDepthOfBinaryTree.java
@@ -0,0 +1,26 @@
+/**
+ * 
+ */
+package com.javaaid.solutions.easy.trees;
+
+/**
+ * @author Kanahaiya Gupta
+ *
+ */
+public class MaximumDepthOfBinaryTree {
+	static class TreeNode {
+		int val;
+		TreeNode left;
+		TreeNode right;
+
+		TreeNode(int x) {
+			val = x;
+		}
+	}
+
+	public int maxDepth(TreeNode root) {
+		if (root == null)
+			return 0;
+		return (1 + Math.max(maxDepth(root.left), maxDepth(root.right)));
+	}
+}
diff --git a/LeetCodeSolutions/EasyLevelSolutions/src/main/java/com/javaaid/solutions/easy/trees/MinimumDepthOfBinaryTree.java b/LeetCodeSolutions/EasyLevelSolutions/src/main/java/com/javaaid/solutions/easy/trees/MinimumDepthOfBinaryTree.java
@@ -0,0 +1,28 @@
+/**
+ * 
+ */
+package com.javaaid.solutions.easy.trees;
+
+/**
+ * @author Kanahaiya Gupta
+ *
+ */
+public class MinimumDepthOfBinaryTree {
+	static class TreeNode {
+		int val;
+		TreeNode left;
+		TreeNode right;
+
+		TreeNode(int x) {
+			val = x;
+		}
+	}
+
+	public int minDepth(TreeNode root) {
+		if (root == null)
+			return 0;
+		if (root.left == null || root.right == null)
+			return (1 + Math.max(minDepth(root.left), minDepth(root.right)));
+		return (1 + Math.min(minDepth(root.left), minDepth(root.right)));
+	}
+}
diff --git a/LeetCodeSolutions/EasyLevelSolutions/src/main/java/com/javaaid/solutions/easy/trees/PathSum.java b/LeetCodeSolutions/EasyLevelSolutions/src/main/java/com/javaaid/solutions/easy/trees/PathSum.java
@@ -0,0 +1,30 @@
+/**
+ * 
+ */
+package com.javaaid.solutions.easy.trees;
+
+/**
+ * @author Kanahaiya Gupta
+ *
+ */
+public class PathSum {
+	static class TreeNode {
+		int val;
+		TreeNode left;
+		TreeNode right;
+
+		TreeNode(int x) {
+			val = x;
+		}
+	}
+
+	public boolean hasPathSum(TreeNode root, int sum) {
+		if (root == null)
+			return false;
+		if (root.left == null && root.right == null && sum - root.val == 0)
+			return true;
+		return hasPathSum(root.left, sum - root.val) || hasPathSum(root.right, sum - root.val);
+
+	}
+
+}
diff --git a/LeetCodeSolutions/EasyLevelSolutions/src/main/java/com/javaaid/solutions/easy/trees/SameTree.java b/LeetCodeSolutions/EasyLevelSolutions/src/main/java/com/javaaid/solutions/easy/trees/SameTree.java
@@ -0,0 +1,28 @@
+/**
+ * 
+ */
+package com.javaaid.solutions.easy.trees;
+
+/**
+ * @author Kanahaiya Gupta
+ *
+ */
+public class SameTree {
+	static class TreeNode {
+		int val;
+		TreeNode left;
+		TreeNode right;
+
+		TreeNode(int x) {
+			val = x;
+		}
+	}
+
+	public boolean isSameTree(TreeNode p, TreeNode q) {
+		if (p == null && q == null)
+			return true;
+		if (p == null && q != null || q == null && p != null)
+			return false;
+		return (p.val == q.val) && isSameTree(p.left, q.left) && isSameTree(p.right, q.right);
+	}
+}
diff --git a/LeetCodeSolutions/MediumLevelSolutions/src/main/java/com/javaaid/solutions/medium/trees/BinaryTreeInorderTraversal.java b/LeetCodeSolutions/MediumLevelSolutions/src/main/java/com/javaaid/solutions/medium/trees/BinaryTreeInorderTraversal.java
@@ -0,0 +1,38 @@
+/**
+ * 
+ */
+package com.javaaid.solutions.medium.trees;
+
+import java.util.ArrayList;
+import java.util.List;
+
+/**
+ * @author Kanahaiya Gupta
+ *
+ */
+public class BinaryTreeInorderTraversal {
+
+	static class TreeNode {
+		int val;
+		TreeNode left;
+		TreeNode right;
+
+		TreeNode(int x) {
+			val = x;
+		}
+	}
+
+	public List<Integer> inorderTraversal(TreeNode root) {
+		List<Integer> list = new ArrayList<Integer>();
+		inorderTraversalUtil(root, list);
+		return list;
+	}
+
+	public void inorderTraversalUtil(TreeNode root, List<Integer> list) {
+		if (root != null) {
+			inorderTraversalUtil(root.left, list);
+			list.add(root.val);
+			inorderTraversalUtil(root.right, list);
+		}
+	}
+}
diff --git a/LeetCodeSolutions/MediumLevelSolutions/src/main/java/com/javaaid/solutions/medium/trees/ValidateBinarySearchTree.java b/LeetCodeSolutions/MediumLevelSolutions/src/main/java/com/javaaid/solutions/medium/trees/ValidateBinarySearchTree.java
@@ -0,0 +1,38 @@
+/**
+ * 
+ */
+package com.javaaid.solutions.medium.trees;
+
+/**
+ * @author Kanahaiya Gupta
+ *
+ */
+public class ValidateBinarySearchTree {
+
+	static class TreeNode {
+		int val;
+		TreeNode left;
+		TreeNode right;
+
+		TreeNode(int x) {
+			val = x;
+		}
+	}
+
+	public boolean isValidBST(TreeNode root) {
+		return validateBSTUtil(root, null);
+	}
+
+	private boolean validateBSTUtil(TreeNode root, Integer prevValue) {
+		if (root == null)
+			return true;
+		if (!validateBSTUtil(root.left, prevValue))
+			return false;
+		if (prevValue != null && prevValue >= root.val)
+			return false;
+		prevValue = root.val;
+		if (!validateBSTUtil(root.right, prevValue))
+			return false;
+		return true;
+	}
+}
