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  Question: Postfix expression evaluation A string containing the postfix expression is given to you. Evaluate it and print the single integer giving the answer. Input Description: The first line of the input is a string N, containing operators and numbers separated by a single space which forms a postfix expression. Output Description: Evaluate the post expression and print the result. Sample Input: 5 3 1 * + 9 - Sample Output: -1 Answer:  Steps to evaluate a prefix expression: Split the prefix expression based on space (" ") or blank string ("") as per the given input. Store the split characters in an array. Create an evaluation array with no elements (blank array). Iterate through the elements of the characters array. If the character is a number, simply push the character into the evaluation array. if the character is an operator (+, -, *, /, %), then pop 2 elements from the evaluation array. Store the first popped number as the right Operand and the second as t...

  Question: Prefix expression evaluation A string containing the prefix expression is given to you. Evaluate it and print the single integer giving the answer. Input Description: You are given a string ‘s’. Output Description: Print the evaluated answer of that string. Sample Input: +23 Sample Output: 5 Answer:  Steps to evaluate a prefix expression: Split the prefix expression based on space (" ") or blank string ("") as per the given input. Store the split characters in an array and reverse the array. Create an evaluation array with no elements (blank array). Iterate through the elements of the characters array. If the character is a number, simply push the character into the evaluation array. if the character is an operator (+, -, *, /, %), then pop 2 elements from the evaluation array. Store the first popped number as the left Operand and the second as the right Operand.  Calculate the result using the operands and current operator. [left operand (operator) righ...

Question:  Given a string S of length N.  Print all permutations of the string in separate lines. Input Size: 1 <= N <= 100000 Sample Testcases : INPUT: 123 OUTPUT: 123 231 321 213 312 132 Answer:  Steps to find all permutations of any number: We are going to use Recursion for calculating the permutations. Create a method called "getPermutations", and create a Permutations array inside the method that will hold all the permutations. Let's start with the base condition (Where the recursion stops). The base condition will be when the number has only one digit simply add it to the permutations array and return the array. If the number has more digits, then iterate through all the digits. On each iteration, find the current digit (store it in one variable) and find all other digits (store it in another variable). Call the recursive function "getPermutations" and pass the other digits variable created in the above step. We will expect this to return an array of...