2 docs tagged with "combinatorics"

Given an integer array nums, return the total number of "partners" in the array.

This question is asked by Google. A ball is dropped into a special Galton board where at each level in the board the ball can only move right or down. Given that the Galton board has M rows and N columns, return the total number of unique ways the ball can arrive at the bottom right cell of the Galton board.