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Technical articles with clear explanations and examples
Find a point such that sum of the Manhattan distances is minimize in C++
Suppose we have n different points in K dimension space, the value of n is in range (2, 105), and value of k in range (1 to 5). We have to determine the point such that the sum of Manhattan distance from resultant point to n points is minimized.The Manhattan distance between two points P1(x1, y1) and P2(x2, y2), is |x1 – x2| + |y1 – y2|. Suppose dimension is 3, and there are three points like (1, 1, 1), (2, 2, 2), (3, 3, 3), then the output will be (2, 2, 2).To solve this problem, we have to ...
Read MoreThe Match Operator in Perl
The match operator m// in Perl, is used to match a string or statement to a regular expression. For example, to match the character sequence "foo" against the scalar $bar, you might use a statement like this −Example#!/usr/bin/perl $bar = "This is foo and again foo"; if ($bar =~ /foo/) { print "First time is matching"; } else { print "First time is not matching"; } $bar = "foo"; if ($bar =~ /foo/) { print "Second time is matching"; } else { print "Second time is not matching"; }When above program is executed, it ...
Read MoreMatching Only Once in Perl
There is a simpler version of the match operator in Perl - the ?PATTERN? operator. This is basically identical to the m// operator except that it only matches once within the string you are searching between each call to reset.For example, you can use this to get the first and last elements within a list −Example#!/usr/bin/perl @list = qw/food foosball subeo footnote terfoot canic footbrdige/; foreach (@list) { $first = $1 if /(foo.*?)/; $last = $1 if /(foo.*)/; } print "First: $first, Last: $last";When the above program is executed, it produces the following result −First: foo, Last: footbrdige
Read MoreThe Substitution Operator in Perl
The substitution operator s/// in Perl is really just an extension of the match operator that allows you to replace the text matched with some new text. The basic form of the operator is −s/PATTERN/REPLACEMENT/;The PATTERN is the regular expression for the text that we are looking for. The REPLACEMENT is a specification for the text or regular expression that we want to use to replace the found text with. For example, we can replace all occurrences of dog with cat using the following regular expression −Example#/user/bin/perl $string = "The cat sat on the mat"; $string =~ s/cat/dog/; print "$string";When the above program is ...
Read MoreFind All Duplicate Subtrees in C++
Consider we have a binary tree. We have to find if there are some duplicate subtrees in the tree or not. Suppose we have a binary tree like below −There are two identical subtrees of size 2. In each subtree D, BD and BE both are also duplicate subtrees We can solve this problem by using tree serialization and hashing process. We will store the inorder traversal of subtrees in the hash table. We will insert opening and closing parenthesis for empty nodes.Example#include #include #include #include using namespace std; const char MARKER = '$'; struct Node ...
Read MoreFind all factorial numbers less than or equal to n in C++
Here we will see how to print all factorial numbers less than or equal to n, a number N is said to be factorial number if it is a factorial of a positive number. So some factorial numbers are 1, 2, 6, 24, 120.To print factorial numbers, we do not need to find the factorial directly. Starting from i = 1, print factorial*i. Initially factorial is 1. Let us see the code for better understanding.Example#include using namespace std; void getFactorialNumbers(int n) { int fact = 1; int i = 2; while(fact
Read MoreFind all pairs (a, b) in an array such that a % b = k in C++
Suppose we have an array A, from that array, we have to get all pairs (a, b) such that the a%b = k. Suppose the array is A = [2, 3, 4, 5, 7], and k = 3, then pairs are (7, 4), (3, 4), (3, 5), (3, 7).To solve this, we will traverse the list and check whether the given condition is satisfying or not.Example#include using namespace std; bool displayPairs(int arr[], int n, int k) { bool pairAvilable = true; for (int i = 0; i < n; i++) { for (int j = 0; j < n; j++) { if (arr[i] % arr[j] == k) { cout
Read MoreGrouping Matching in Perl
From a regular-expression point of view in Perl, there is no difference between the following two expressions except that the former is slightly clearer.$string =~ /(\S+)\s+(\S+)/; and $string =~ /\S+\s+\S+/;However, the benefit of grouping is that it allows us to extract a sequence from a regular expression. Groupings are returned as a list in the order in which they appear in the original. For example, in the following fragment we have pulled out the hours, minutes, and seconds from a string.my ($hours, $minutes, $seconds) = ($time =~ m/(\d+):(\d+):(\d+)/);As well as this direct method, matched groups are also available within the ...
Read MoreFind all pairs (a,b) and (c,d) in array which satisfy ab = cd in C++
Suppose we have an array A, from that array, we have to choose two pairs (a, b) and (c, d), such that ab = cd. Let the array A = [3, 4, 7, 1, 2, 9, 8]. The output pairs are (4, 2) and (1, 8). To solve this, we will follow these steps −For i := 0 to n-1, dofor j := i + 1 to n-1, doget product = arr[i] * arr[j]if product is not present in the hash table, then Hash[product] := (i, j)if product is present in the hash table, then print previous and current elements.Example#include ...
Read MoreThe G Assertion in Perl
The \G assertion in Perl allows you to continue searching from the point where the last match occurred. For example, in the following code, we have used \G so that we can search to the correct position and then extract some information, without having to create a more complex, single regular expression −Example#!/usr/bin/perl $string = "The time is: 12:31:02 on 4/12/00"; $string =~ /:\s+/g; ($time) = ($string =~ /\G(\d+:\d+:\d+)/); $string =~ /.+\s+/g; ($date) = ($string =~ m{\G(\d+/\d+/\d+)}); print "Time: $time, Date: $date";When the above program is executed, it produces the following result −Time: 12:31:02, Date: 4/12/00The \G assertion is actually ...
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