Suppose we have a binary tree, we have to check whether for every node in the tree except leaves, its value is same as the sum of its left child's value and its right child's value or not.So, if the input is likethen the output will be TrueTo solve this, we will follow these steps −Define a function dfs() . This will take rootif root is null, thenreturn Trueif left of root is null and right of root is null, thenreturn Trueleft := 0if left of root is not null, thenleft := value of left of rootright := 0if right ... Read More

Suppose we have a list of numbers called nums and another value k, we have to find three unique entries in nums (a, b, c) such that |a + b + c − k| is minimized and return the absolute difference.So, if the input is like nums = [2, 5, 25, 6] k = 14, then the output will be 1 as if we take [2, 5, 6] will get us closest to 14 and the absolute difference is |13 − 14| = 1.To solve this, we will follow these steps −sort the list numsans := 1^9for i in range ... Read More

Suppose we have a list of numbers called nums and another value target, we have to find the number of triples (i < j < k) that exist such that nums[i] + nums[j] + nums[k] < target.So, if the input is like nums = [−2, 6, 4, 3, 8], target = 12, then the output will be 5, as the triplets are: [−2, 6, 4], [−2, 6, 3], [−2, 4, 3], [−2, 4, 8], [−2, 3, 8]To solve this, we will follow these steps −sort the list numsans := 0n := size of numsfor i in range 0 to n−1, ... Read More

Suppose we have a list of numbers called nums and another value k, we have to check whether we can find three unique elements in the list whose sum is k.So, if the input is like nums = [11, 4, 6, 10, 5, 1] k = 20, then the output will be True, as we have numbers [4, 6, 10] whose sum is 20.To solve this, we will follow these steps −sort the list numsl := 0, r := size of nums − 1while l < r − 1, dot := k − nums[l] − nums[r]if nums[r − 1] < ... Read More

Suppose we have a binary tree; we have to find the sum of values of its deepest leaves. So if the tree is like −Then the output will be 11.To solve this, we will follow these steps −Define a map m, and maxDepthDefine a recursive method solve(), this will take node and level, initially level is 0if node is not present, then returnmaxDepth := max of level and maxDepthincrease m[level] by value of nodesolve(left of node, level + 1)solve(right of node, level + 1)In the main method, setup maxDepth := 0, then solve(root, 0)return m[maxDepth]Let us see the following implementation ... Read More

Suppose we have a binary tree we have to find the sum of all right leaves in a given binary tree.So, if the input is likethen the output will be 17, as there are two right leaves in the binary tree, with values 7 and 10 respectively.To solve this, we will follow these steps −Define a function dfs(), this will take node, add, if node is null, then −returnif left of node is null and right of node is null and add is non-zero, then −ret := ret + val of nodedfs(left of node, false)dfs(right of node, true)From the main ... Read More

Suppose we have a list of numbers called nums and a value k, we have to check whether there are four unique elements in the list that add up to k.So, if the input is like nums = [11, 4, 6, 10, 5, 1] k = 25, then the output will be True, as we have [4, 6, 10, 5] whose sum is 25.To solve this, we will follow these steps −sort the list numsn := size of numsfor i in range 0 to n − 4, dofor j in range i + 1 to n − 3, dol := ... Read More

Suppose we have a partially filled Sudoku grid and we have to solve this. We know that Sudoku is a 9 × 9 number grid, and the whole grid are also divided into 3 × 3 boxes There are some rules to solve the Sudoku.We have to use digits 1 to 9 for solving this problem.One digit cannot be repeated in one row, one column or in one 3 × 3 box.Using backtracking algorithm, we will try to solve Sudoku problem. When some cell is filled with a digit, it checks whether it is valid or not. When it is ... Read More

Suppose we have two binary trees. We have to check whether second tree is a subtree of first one or not.So, if the input is likethen the output will be True.To solve this, we will follow these steps −Define a function solve() . This will take root, targetif root is null and target is also null, thenreturn Trueif root is null or target is null, thenreturn Falseif value of root is same as value of target, thenreturn solve(left of root, left of target) and solve(right of root, right of target)otherwise, return solve(left of root, target) or solve(right of root, target)Let ... Read More

Suppose we have a list of numbers called nums, we select a subsequence of strictly increasing values, where the differences of each two numbers is the same as the differences of their two indices. So we have to find the maximum sum of such a subsequence.So, if the input is like nums = [6, 7, 9, 9, 8, 5], then the output will be 22, as we select the subsequence [6, 7, 9] whose indices are [0, 1, 3]. The differences between each consecutive numbers is [1, 2] which is same as the differences of their indices.To solve this, we ... Read More