Initial data commit

Task/Ethiopian-multiplication/Java/ethiopian-multiplication-1.java

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+import java.util.HashMap;
+import java.util.Map;
+import java.util.Scanner;
+public class Mult{
+  public static void main(String[] args){
+    Scanner sc = new Scanner(System.in);
+    int first = sc.nextInt();
+    int second = sc.nextInt();
+
+    if(first < 0){
+        first = -first;
+        second = -second;
+    }
+
+    Map<Integer, Integer> columns = new HashMap<Integer, Integer>();
+        columns.put(first, second);
+    int sum = isEven(first)? 0 : second;
+    do{
+      first = halveInt(first);
+      second = doubleInt(second);
+      columns.put(first, second);
+      if(!isEven(first)){
+          sum += second;
+      }
+    }while(first > 1);
+
+    System.out.println(sum);
+  }
+
+  public static int doubleInt(int doubleMe){
+    return doubleMe << 1; //shift left
+  }
+
+  public static int halveInt(int halveMe){
+    return halveMe >>> 1; //shift right
+  }
+
+  public static boolean isEven(int num){
+    return (num & 1) == 0;
+  }
+}

Task/Ethiopian-multiplication/Java/ethiopian-multiplication-2.java

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+/**
+ * This method will use ethiopian styled multiplication.
+ * @param a Any non-negative integer.
+ * @param b Any integer.
+ * @result a multiplied by b
+ */
+public static int ethiopianMultiply(int a, int b) {
+  if(a==0 || b==0) {
+    return 0;
+  }
+  int result = 0;
+  while(a>=1) {
+    if(!isEven(a)) {
+      result+=b;
+    }
+    b = doubleInt(b);
+    a = halveInt(a);
+  }
+  return result;
+}
+
+/**
+ * This method is an improved version that will use
+ * ethiopian styled multiplication, and also
+ * supports negative parameters.
+ * @param a Any integer.
+ * @param b Any integer.
+ * @result a multiplied by b
+ */
+public static int ethiopianMultiplyWithImprovement(int a, int b) {
+  if(a==0 || b==0) {
+    return 0;
+  }
+  if(a<0) {
+    a=-a;
+    b=-b;
+  } else if(b>0 && a>b) {
+    int tmp = a;
+    a = b;
+    b = tmp;
+  }
+  int result = 0;
+  while(a>=1) {
+    if(!isEven(a)) {
+      result+=b;
+    }
+    b = doubleInt(b);
+    a = halveInt(a);
+  }
+  return result;
+}