//Given n non-negative integers representing an elevation map where the width of // each bar is 1, compute how much wate

//Given an unsorted integer array nums, return the smallest missing positive int //eger. // // You must implement an al

//The count-and-say sequence is a sequence of digit strings defined by the recur //sive formula: // // // countAndSay(

//Determine if a 9 x 9 Sudoku board is valid. Only the filled cells need to be v //alidated according to the following r

//Given an array of integers nums sorted in non-decreasing order, find the start //ing and ending position of a given ta