Suppose we have a digit, now if we rotate that digit by 180 degrees to form new digits. When 0, 1, 6, 8, 9 are rotated 180 degrees, they become 0, 1, 9, 8, 6 respectively. But when 2, 3, 4, 5 and 7 are rotated 180 degrees, they become ... Read More

Suppose we have an integer d between 0 and 9, we also have two positive integers low and high as lower and upper bounds, respectively. We have to find the number of times that d occurs as a digit in all integers between low and high, including the bounds low ... Read More

Suppose we have an array A of integers, we have to find the number of non-empty continuous subarrays that satisfy this condition: The leftmost element of the subarray is not larger than other elements in the subarray.So, if the input is like [1, 4, 2, 5, 3], then the output ... Read More

Suppose we have one horizontal number line. On that number line, we have gas stations at positions stations[0], stations[1], ..., stations[N-1], where N = size of the stations array. Now, we add K more gas stations so that D, the maximum distance between adjacent gas stations, is minimized. We have ... Read More

Suppose we have a simple expression string and we have to Implement a basic calculator to evaluate that expression. The expression string may contain opening and closing parentheses, the plus + or minus sign -, non-negative integers and empty spaces. The expression string contains only non-negative integers, +, -, *, ... Read More

Suppose we have given a list of schedules of employees; this represents the working time for each employee. Now suppose each employee has a list of non-overlapping Intervals, these intervals are sorted. We have to find the list of finite intervals representing the common, positive-length free time for all employees, ... Read More

Suppose we have two strings S and T, we have to find the minimum substring W of S, so that T is a subsequence of W. If there is no such window in S that covers all characters in T, then return empty string. If there are multiple such windows, ... Read More

Suppose we have a non-empty 2D binary array called grid, here an island is a group of 1's (representing land) connected 4-directionally. We can also assume all four edges of the grid are surrounded by water.We have to count the number of distinct islands. An island is considered to be ... Read More

Suppose we have N bulbs in a row and they are numbered from 1 to N. At first, all the bulbs are off. We can turn on exactly one bulb everyday until all bulbs are on after N days. If we have an array bulbs of length N where bulbs[i] ... Read More

Suppose we have an integer n, we have to return nth integer after following this operation: Start from integer 1, remove any integer that contains 9 such as 9, 19, 29... So now, we will have a new integer sequence like 1, 2, 3, 4, 5, 6, 7, 8, 10, ... Read More