Ethiopian multiplication: Difference between revisions

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   }
 }</lang>
+An optimised varient.
+<lang java5>
+  /**
+   * This method will use etiopian styled multiplication.
+   * @param a Any non-negative integer.
+   * @param b Any integer.
+   * @result a multiplied by b
+   */
+  public static int etiopianMultiply(int a, int b) {
+    if(a==0 || b==0) {
+      return 0;
+    }
+    int result = 0;
+    while(a>=1) {
+      if((a&1) == 1) {
+        result+=b;
+      }
+      b<<=1;
+      a>>>=1;
+    }
+    return result;
+  }
+  /**
+   * This method is an improved version that will use
+   * etiopian styled multiplication, but can fully
+   * support negative parameters.
+   * @param a Any integer.
+   * @param b Any integer.
+   * @result a multiplied by b
+   */
+  public static int etiopianMultiplyWithImprovement(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((a&1) == 1) {
+        result+=b;
+      }
+      b<<=1;
+      a>>>=1;
+    }
+    return result;
+  }
+</lang>
 == {{header|JavaScript}} ==