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/* ************************************************************** * C++ Mathematical Expression Toolkit Library * * * * ExprTk Pascal's Triangle * * Author: Arash Partow (1999-2024) * * URL: https://www.partow.net/programming/exprtk/index.html * * * * Copyright notice: * * Free use of the Mathematical Expression Toolkit Library is * * permitted under the guidelines and in accordance with the * * most current version of the MIT License. * * https://www.opensource.org/licenses/MIT * * SPDX-License-Identifier: MIT * * * ************************************************************** */ #include #include #include "exprtk.hpp" template void pascals_triangle() { typedef exprtk::symbol_table symbol_table_t; typedef exprtk::expression expression_t; typedef exprtk::parser parser_t; typedef exprtk::function_compositor compositor_t; typedef typename compositor_t::function function_t; exprtk::rtl::io::package io_package; symbol_table_t symbol_table; symbol_table.add_package(io_package); symbol_table.add_function("print_coeff", [](T t) { printf("%6d", static_cast(t)); return T(0); }); compositor_t compositor(symbol_table); compositor.add( function_t("n_choose_k") .vars("n","k") .expression ( " switch " " { " " case n <= k : 1; " " case k <= 0 : 1; " " default : n_choose_k(n - 1, k - 1) + " " n_choose_k(n - 1, k ) ; " " } " )); const std::string pascals_triangle_program = " const var rows := 20; " " " " for (var n := 0; n < rows; n += 1) " " { " " for (var s := 0; s <= (rows - n) - 2; s += 1) " " { " " print(' '); " " }; " " " " for (var k := 0; k <= n; k += 1) " " { " " print_coeff(n_choose_k(n,k)); " " }; " " " " println(); " " } "; expression_t expression; expression.register_symbol_table(symbol_table); parser_t parser; parser.compile(pascals_triangle_program,expression); expression.value(); } int main() { pascals_triangle(); return 0; }