Write a java code to check balanced parentheses in an expression using stack.
Given an expression containing characters ‘{‘,’}’,'(‘,’)’,'[‘,’]’. We have to write a code to check whether an input string has valid parentheses.
An input string is valid if:
Open brackets must be closed by the same type of brackets.
Open brackets must be closed in the correct order.
Example –
i) {[]}) – Invalid
ii) {()}[] – Valid
Write a java program to reverse a string using stack data structure. Given an input string, We have to write a java code to reverse a string using stack.
In my previous tutorial, I have explained java program to reverse a string using recursion.
Before solving this problem, Let’s understand what is a stack data structure.
Find pairs with given sum in a sorted array.
Given an array A of size N. Write a code to find all pairs in the array that sum to a number equal to K. If no such pair exists then output will be –1.
NOTE – The array elements are distinct and in a sorted order.
For example –
Input :
arr[] = {1, 2, 3, 4, 5, 6, 7};
sum = 9
Output:
Pairs with given sum 9 is
Pair (2 , 7 )
Pair (3 , 6 )
Pair (4 , 5 )