#!/usr/bin/env python3
########################################################################
# Solves problem 15 from projectEuler.net.
# Finds the number of routes in a 20x20 sided square.
# Copyright (C) 2010 Santiago Alessandri
#
# This program is free software: you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program. If not, see .
#
# You can contact me at san.lt.ss@gmail.com
# Visit my wiki at http://san-ss.wikidot.com
########################################################################
if __name__ == '__main__':
#Building the matrix
sqre = [[]]
for i in range(21):
sqre[0].append(1)
for i in range(1,21):
row = [1]
for i in range(1,21):
row.append(0)
sqre.append(row)
#Processing the routes
for i in range(1,21):
for j in range(1, 21):
sqre[i][j] = sqre[i-1][j] + sqre[i][j-1]
print("The result is:", sqre[20][20])