Suppose we have an array nums. We have to find number of pairs (i, j) are there such that nums[i] = nums[j] but i is not same as j.So, if the input is like nums = [1, 3, 1, 3, 5], then the output will be 4, because the pairs are (0, 2), (2, 0), (1, 3) and (3, 1)To solve this, we will follow these steps −d := a new mapfor each c in nums, dod[c] := (d[c] + 1) when c is present in d otherwise 1res := 0for each c is in the list of elements (x ... Read More

Suppose we have n balls which are numbered by an array nums, whose size is n and nums[i] represents the number of ball i. Now we have another value k. In each turn we pick k balls from n different balls and find the difference of maximum and minimum values of k balls and store the difference in a table. Then put these k balls again into that pot and pick again until we have selected all possible selections. Finally find the sum of all differences from the table. If the answer is too large, then return result mod 10^9+7.So, ... Read More

Suppose we have two lists nums1 and nums2. Now the constraint is when we merge the order of elements in each list does not change, for example, if the elements are [1, 2, 3] and [4, 5, 6], then some valid merged lists are [1, 4, 2, 3, 5, 6] and [1, 2, 3, 4, 5, 6], there may be some other valid merge sequence. So if we have the size of lists N and M. We have to find number of ways we can merge them to get valid list. If the answer is too large the return result ... Read More

Suppose we have a string s. We have to find all possible combinations of letters of s. If there are two strings with same set of characters, then show the lexicographically smallest of them. And one constraint is each character in s are unique.So, if the input is like s = "pqr", then the output will be ['r', 'qr', 'q', 'pr', 'pqr', 'pq', 'p']To solve this, we will follow these steps −st_arr := a new listfor i in range size of s - 1 to 0, decrease by 1, dofor j in range 0 to size of st_arr - 1, ... Read More

Suppose we have limited coins of denominations (₹1, ₹2, ₹5 and ₹10). We have to find in how many ways can you sum them up to a total of ₹n? We have an array count of size 4, where count[0] indicates coins of ₹1, count[1] indicates coins of ₹2 and so on.So, if the input is like n = 25 count = [7, 3, 2, 2], then the output will be 9.To solve this, we will follow these steps −denom := [1, 2, 5, 10]A := an array of size (n + 1) and fill with 0B := a new ... Read More

Suppose we have to calculate nCr values many times. We can solve this very efficient way. If we store the lower values of nCr we can easily find higher values. So if we have n, we have to find list of nC0 to nCn. If answer is too large then return that modulo 10^9.So, if the input is like n = 6, then the output will be [1, 6, 15, 20, 15, 6, 1].To solve this, we will follow these steps −items := a list with single element 1for r in range 1 to n, doinsert floor of (last element ... Read More

Suppose we want to find the total area covered by two rectilinear rectangles in a 2D plane. Here each rectangle is defined by its bottom left corner and top right corner as shown in the figure.To solve this, we will follow these steps −width_1 := |C-A|, height_1 := |D-B|width_2 := |G-E|, height_2 := |H-F|area := width_1*height_1 + width_2*height_2if (GC) or (F>D) or (HD) or (H

Suppose we have a sequence nums of size n. We have to find the maximum size of subsequence of nums in which every pair (p, q) is a nice pair? A pait is said to be nice pair if and only if it holds at least one of these conditions: 1. The parity of the number of distinct prime divisors of p is equal to that of b. For example, the value 18 has two distinct prime divisors: 2 and 3. 2. The parity of the sum of all positive divisors of p is same as q.So, if the input ... Read More

Suppose we have a number A. We have to generate a large number X by concatenating A, n times in a row and find the value of X modulo m.So, if the input is like A = 15 n = 3 m = 8, then the output will be 3, because the number x will be 151515, and 151515 mod 8 = 3.To solve this, we will follow these steps −if A is same as 0, thenreturn 0an:= Ac:= number of digits in Ac:= 10^cd:= c-1newmod := d*mval := (c ^ n mod newmod) -1val :=(val + newmod) mod newmodan ... Read More

Suppose there is a strange language called Ajob language. It has infinite number of letters. We know n words in this language. The first word is one character long, second one is two character long and so on. And all letters in a word are unique. If we select any one of the n words and form a subsequence from it. The length of the subsequence should be k less than the length of original word. For an example, if the length of the chosen word is say L, then the length of the subsequence should be (L - k). ... Read More