Data commit

Task/Polynomial-long-division/C-sharp/polynomial-long-division.cs

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+using System;
+
+namespace PolynomialLongDivision {
+    class Solution {
+        public Solution(double[] q, double[] r) {
+            Quotient = q;
+            Remainder = r;
+        }
+
+        public double[] Quotient { get; }
+        public double[] Remainder { get; }
+    }
+
+    class Program {
+        static int PolyDegree(double[] p) {
+            for (int i = p.Length - 1; i >= 0; --i) {
+                if (p[i] != 0.0) return i;
+            }
+            return int.MinValue;
+        }
+
+        static double[] PolyShiftRight(double[] p, int places) {
+            if (places <= 0) return p;
+            int pd = PolyDegree(p);
+            if (pd + places >= p.Length) {
+                throw new ArgumentOutOfRangeException("The number of places to be shifted is too large");
+            }
+            double[] d = new double[p.Length];
+            p.CopyTo(d, 0);
+            for (int i = pd; i >= 0; --i) {
+                d[i + places] = d[i];
+                d[i] = 0.0;
+            }
+            return d;
+        }
+
+        static void PolyMultiply(double[] p, double m) {
+            for (int i = 0; i < p.Length; ++i) {
+                p[i] *= m;
+            }
+        }
+
+        static void PolySubtract(double[] p, double[] s) {
+            for (int i = 0; i < p.Length; ++i) {
+                p[i] -= s[i];
+            }
+        }
+
+        static Solution PolyLongDiv(double[] n, double[] d) {
+            if (n.Length != d.Length) {
+                throw new ArgumentException("Numerator and denominator vectors must have the same size");
+            }
+            int nd = PolyDegree(n);
+            int dd = PolyDegree(d);
+            if (dd < 0) {
+                throw new ArgumentException("Divisor must have at least one one-zero coefficient");
+            }
+            if (nd < dd) {
+                throw new ArgumentException("The degree of the divisor cannot exceed that of the numerator");
+            }
+            double[] n2 = new double[n.Length];
+            n.CopyTo(n2, 0);
+            double[] q = new double[n.Length];
+            while (nd >= dd) {
+                double[] d2 = PolyShiftRight(d, nd - dd);
+                q[nd - dd] = n2[nd] / d2[nd];
+                PolyMultiply(d2, q[nd - dd]);
+                PolySubtract(n2, d2);
+                nd = PolyDegree(n2);
+            }
+            return new Solution(q, n2);
+        }
+
+        static void PolyShow(double[] p) {
+            int pd = PolyDegree(p);
+            for (int i = pd; i >= 0; --i) {
+                double coeff = p[i];
+                if (coeff == 0.0) continue;
+                if (coeff == 1.0) {
+                    if (i < pd) {
+                        Console.Write(" + ");
+                    }
+                } else if (coeff == -1.0) {
+                    if (i < pd) {
+                        Console.Write(" - ");
+                    } else {
+                        Console.Write("-");
+                    }
+                } else if (coeff < 0.0) {
+                    if (i < pd) {
+                        Console.Write(" - {0:F1}", -coeff);
+                    } else {
+                        Console.Write("{0:F1}", coeff);
+                    }
+                } else {
+                    if (i < pd) {
+                        Console.Write(" + {0:F1}", coeff);
+                    } else {
+                        Console.Write("{0:F1}", coeff);
+                    }
+                }
+                if (i > 1) Console.Write("x^{0}", i);
+                else if (i == 1) Console.Write("x");
+            }
+            Console.WriteLine();
+        }
+
+        static void Main(string[] args) {
+            double[] n = { -42.0, 0.0, -12.0, 1.0 };
+            double[] d = { -3.0, 1.0, 0.0, 0.0 };
+            Console.Write("Numerator   : ");
+            PolyShow(n);
+            Console.Write("Denominator : ");
+            PolyShow(d);
+            Console.WriteLine("-------------------------------------");
+            Solution sol = PolyLongDiv(n, d);
+            Console.Write("Quotient    : ");
+            PolyShow(sol.Quotient);
+            Console.Write("Remainder   : ");
+            PolyShow(sol.Remainder);
+        }
+    }
+}