dsa questions added

DP/FiboSeries.java

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+package com.DP;public class FiboSeries {
+}

DP/FrogJump2.java

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+package com.DP;public class FrogJump2 {
+}

DP/climbStairs.java

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+package com.DP;public class climbStairs {
+}

DSA/BST.java

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+package com.DSA;public class BST {
+}

DSA/BinaryTree.java

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+package com.DSA;public class BinaryTree {
+}

Exam/tp.java

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+package com.Exam;public class tp {
+}

Java_Classes/Staff.java

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+package com.Java_Classes;public class Staff {
+}

Practice/ExcelSheet.java

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+package com.Practice;
+
+public class ExcelSheet {
+    public static void main(String[] args) {
+        System.out.println(findIndex("ZZZ"));
+    }
+    static int findIndex(String str){
+       return getIndex(str,0);
+    }
+
+    private static int getIndex(String str, int ans) {
+        if(str.isEmpty()){
+            return ans;
+        }
+        int temp = str.charAt(0);//AA  A-->65
+        if(temp < 65 || temp > 90){
+            return 0;
+        }
+        temp = temp % 64 ;
+        ans = 26 * ans + temp;
+       return getIndex(str.substring(1),ans);
+    }
+}

Practice/GoodPosition.java

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+package com.Practice;
+
+public class GoodPosition {
+    public static void main(String[] args) {
+        int [] arr = {1,4,3};
+        System.out.println(findPosition(arr , 3 , 3));
+    }
+    static int findPosition(int [] arr , int n,int k ){
+        int sum = 0;
+        for(int i =0; i < n ; i++ ){
+            sum = sum + arr[i];
+        }
+        return findPos(arr,0,k,sum , 0);
+    }
+
+    private static int findPos(int[] arr, int i, int k, int sum,int ans) {
+        if(i == arr.length){
+            return ans;
+        }
+        if((arr[i]+k) > (sum-arr[i])){
+            ans++;
+            return findPos(arr , i+1,k,sum,ans);
+        }else{
+            return findPos(arr , i+1,k,sum,ans);
+        }
+    }
+
+
+}

Practice/LargestAreaHistogram.java

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+package com.Practice;
+
+import java.util.Stack;
+
+//leetcode 84
+public class LargestAreaHistogram {
+    public static void main(String[] args) {
+        int []heights ={2,1,5,6,2,3};
+        System.out.println(largestRectangleArea(heights));
+    }
+
+    public static int largestRectangleArea(int [] heights){
+        Stack<Integer>stack = new Stack<>();
+        int max = 0;
+
+        stack.push(0);
+        for(int i = 1; i< heights.length ; i++){
+            while(!stack.isEmpty() && heights[i] < heights[stack.peek()]){
+                max = getMax(heights,stack,max,i);
+            }
+            stack.push(i);
+        }
+        int i = heights.length;
+        while(!stack.isEmpty()){
+            max = getMax(heights,stack,max,i);
+        }
+        return max;
+    }
+    static int getMax(int [] heights , Stack<Integer> stack , int max, int index){
+        int area;
+        int popped =stack.pop();
+        if(stack.isEmpty()){
+            area = heights[popped] * index;
+        }else{
+            area = heights[popped] * (index-1-stack.peek());
+        }
+    return Math.max(max,area);
+    }
+}

Practice/MaxDifference.java

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+package com.Practice;
+
+import java.util.Arrays;
+
+public class MaxDifference {
+    public static void main(String[] args) {
+        int [] arr = {1,6,3,2};
+        Arrays.sort(arr);
+        int maxDifference = arr[arr.length-1] - arr[0];
+        System.out.println(maxDifference);
+
+
+    }
+}

Practice/MergeAlternateString.java

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+package com.Practice;
+
+public class MergeAlternateString {
+    public static void main(String[] args) {
+        //1768. Merge Strings Alternately
+
+    }
+    public static String mergeAlternately(String word1, String word2) {
+        StringBuilder result = new StringBuilder();
+        int i = 0;
+        while (i < word1.length() || i < word2.length()) {
+            if (i < word1.length()) {
+                result.append(word1.charAt(i));
+            }
+            if (i < word2.length()) {
+                result.append(word2.charAt(i));
+//                result.append
+            }
+            i++;
+        }
+        return result.toString();
+    }
+}

Practice/MinDifference.java

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+package com.Practice;
+
+import java.util.Arrays;
+
+public class MinDifference {
+    public static void main(String[] args) {
+        int [] arr = {90,80,70,75};
+        System.out.println(minDiff(arr,2));
+    }
+    static int minDiff(int [] arr,int num){
+        if(arr.length == 1 || arr.length<num){
+            return 0;
+        }
+        Arrays.sort(arr);
+        int j = num-1;
+        int difference  = Integer.MAX_VALUE;
+        int temp;
+        for(int i =0;i< arr.length && j< arr.length;i++,j++){
+            temp = arr[j] - arr[i];
+            if(difference > temp){
+                difference = temp;
+            }
+        }
+        return difference;
+    }
+}