RandomProblem005.java evaluating polynomial using Horner method

shekhargulati · shekhargulati · commit 97f2a6965fd6 · 2016-02-13T21:14:39.000+05:30
diff --git a/java8/src/main/java/com/shekhargulati/ninetynine_problems/java8/_00_random/algebra/RandomProblem005.java b/java8/src/main/java/com/shekhargulati/ninetynine_problems/java8/_00_random/algebra/RandomProblem005.java
@@ -0,0 +1,26 @@
+package com.shekhargulati.ninetynine_problems.java8._00_random.algebra;
+
+/**
+ * Write a program that can evaluate a polynomial
+ * p(x) = ao + a1x^1 + a2x^2 + .... + anx^n
+ * <p>
+ * https://en.wikipedia.org/wiki/Horner%27s_method
+ */
+public class RandomProblem005 {
+
+    public static int evaluatePolynomialAt(int n, int a, int x) {
+        int result = a;
+        for (int i = 1; i <= n; i++) {
+            result = result + Double.valueOf(a * Math.pow(x, i)).intValue();
+        }
+        return result;
+    }
+
+    public static int eval(int n, int a, int x) {
+        int res = 0;
+        for (int i = n; i >= 0; i--) {
+            res = (res * x) + a;
+        }
+        return res;
+    }
+}
diff --git a/java8/src/test/java/com/shekhargulati/ninetynine_problems/java8/_00_random/algebra/RandomProblem005Test.java b/java8/src/test/java/com/shekhargulati/ninetynine_problems/java8/_00_random/algebra/RandomProblem005Test.java
@@ -0,0 +1,12 @@
+package com.shekhargulati.ninetynine_problems.java8._00_random.algebra;
+
+import org.junit.Test;
+
+public class RandomProblem005Test {
+
+    @Test
+    public void shouldEvaluateAPolynomial() throws Exception {
+        System.out.println(RandomProblem005.eval(10, 5, 2));
+        System.out.println(RandomProblem005.evaluatePolynomialAt(10, 5, 2));
+    }
+}
