# Category Archives: Backtracking

## Check if a given string is sum-stringAugust 25, 2017

Given a string of digits, determine whether it is a ‘sum-string’. A string S is called a sum-string if a rightmost substring can be written… Read More »

## Combinational SumJuly 29, 2017

Given an array of positive integers arr[] and a sum x, find all unique combinations in arr[] where the sum is equal to x. The… Read More »

## Combinations where every element appears twice and distance between appearances is equal to the valueJune 6, 2017

Given a positive number n, we need to find all the combinations of 2*n elements such that every element from 1 to n appears exactly… Read More »

## Top 20 Backtracking Algorithm Interview QuestionsApril 28, 2017

N Queens Problem Warnsdorff’s Algorithm Word Break Problem Remove Invalid Parenthesis Match a pattern and string using regular expression Find Path from corner cell to… Read More »

## Warnsdorff’s algorithm for Knight’s tour problemMarch 28, 2017

Problem : A knight is placed on the first block of an empty board and, moving according to the rules of chess, must visit each… Read More »

## Printing all solutions in N-Queen ProblemFebruary 19, 2017

The N Queen is the problem of placing N chess queens on an N×N chessboard so that no two queens attack each other. For example,… Read More »

## Print all palindromic partitions of a stringJanuary 6, 2017

Given a string s, partition s such that every string of the partition is a palindrome. Return all possible palindrome partitioning of s. Example :… Read More »

## Word Break Problem using BacktrackingJanuary 1, 2017

Given a valid sentence without any spaces between the words and a dictionary of valid English words, find all possible ways to break the sentence… Read More »

## Partition of a set into K subsets with equal sumDecember 14, 2016

Given an integer array of N elements, the task is to divide this array into K non-empty subsets such that the sum of elements in… Read More »

## Remove Invalid ParenthesesOctober 9, 2016

An expression will be given which can contain open and close parentheses and optionally some characters, No other operator will be there in string. We… Read More »

## Find shortest safe route in a path with landminesAugust 14, 2016

Given a path in the form of a rectangular matrix having few landmines arbitrarily placed (marked as 0), calculate length of the shortest safe route… Read More »

## Longest Possible Route in a Matrix with HurdlesAugust 4, 2016

Given an M x N matrix, with a few hurdles arbitrarily placed, calculate the length of longest possible route possible from source to destination within… Read More »

## Match a pattern and String without using regular expressionsJuly 6, 2016

Given a string, find out if string follows a given pattern or not without using any regular expressions. Examples: Input: string – GraphTreesGraph pattern -… Read More »

## Find Maximum number possible by doing at-most K swapsJune 25, 2016

Given a positive integer, find maximum integer possible by doing at-most K swap operations on its digits. Examples: Input: M = 254, K = 1… Read More »

## Find paths from corner cell to middle cell in mazeJune 17, 2016

Given a square maze containing positive numbers, find all paths from a corner cell (any of the extreme four corners) to the middle cell. We… Read More »