還不能處理負數和小數點
package?s1;
import?java.util.Stack;
import?java.util.Vector;
/**?*//**
?*?A?multiply?simulation
?*?for?example?:?
?*?56?X?67?=?
?*
?*?????56
?*???x?67
?*?----------
?*????392
?*???336
?*------------
?*???3752
?*
?*?So?,in?this?way,We?can?calculation?very?very?big?number,for?example:?299^133?etc.?
?*?
?*?@author?Urashima?
?*
?*/
public?class?BigNumberMultiply?extends?BaseNumberOperation
{
????
????//each?array?indicates?a?param
????private?Integer[]?paramFirst,paramSecond;
????
????//main?method????
????public?String?calculate(String?param1,String?param2){
????????paramFirst??=?convert(param1);
????????paramSecond?=?convert(param2);
????????//multiply?each?bit,from?low?to?high
????????int?indexFirst?=?paramFirst.length?-?1;
????????int?indexSecond?=?paramSecond.length?-?1;
????????//multiply?results?for?each?bit
????????Vector<Integer[]>?branchResults?=?new?Vector<Integer[]>();
????????for(;indexSecond?>?-1;indexSecond--){
????????????branchResults.add(branchMultiply(paramFirst,paramSecond[indexSecond]));
????????}
????????String?finalResult?=?branchAddTogether(branchResults);
????????return?finalResult;
????}
????
????private?Integer[]?branchMultiply(Integer[]?upper,Integer?down){
????????Stack<Integer>?results?=?new?Stack<Integer>();
????????//todo?:?all?core?gose?here
????????int?carryFlag?=?0;
????????for(int?index?=?upper.length-1?;index?>?-1;index--){
????????????int?r1?=?down;
????????????int?r2?=?upper[index];
????????????int?r0?=?r1?*?r2?+?carryFlag;
????????????carryFlag?=?(int)(r0/10);
????????????int?r3?=?r0?-?(?10?*?carryFlag?);
????????????if(index!=0)
????????????????results.push(r3);
????????????else
??????????????????results.push(r0);????
????????}
????????//sorts?out?and?return
????????Integer[]?branchResult?=?new?Integer[results.size()];
????????results.toArray(branchResult);
????????//System.out.println?(branchResult.toString());
????????return?branchResult;
????}????
????????
????private?String?branchAddTogether(Vector<Integer[]>?v){
????????Vector<String>?params?=?new?Vector<String>();
????????//TODO:?fix?bug#001
????????int?bi?=?0;
????????for(Integer[]?pps?:?v){
????????????//revers?pps
????????????Integer[]?rpps?=?new?Integer[pps.length];
????????????System.arraycopy(pps,0,rpps,0,pps.length);
????????????for(int?k?=?pps.length-1?;?k?>?-1?;?k--?){
????????????????rpps[pps.length-1-k]?=?pps[k];
????????????}
????????????v.set(bi++,rpps);
????????}
????????//sort?out?data,add?increamental?0?to?each?bit
????????for(Integer[]?ii?:?v){
????????????String?pa?=?"";
????????????for(Integer?i?:?ii){
????????????????pa?+=?i;
????????????}
????????????params.add(pa);
????????}?????
????????int?incr?=?0;
????????for(int?idx?=?0?;?idx?<?params.size();?idx?++){
????????????String?s?=?params.get(idx);
????????????for(int?i?=?0?;?i?<?incr?;?i?++){
????????????????s?+=?"0";
????????????}
????????????params.set(idx,s);
????????????//System.out.println?(s);
????????????incr++;
????????}
????????//convert?back?to?int[]
????????for(int?i?=?0?;?i?<?params.size();i++){
????????????String?ctt?=?params.get(i);
????????????//System.out.println?(ctt);
????????????v.set(i,convert(ctt));
????????}
????????//add?them?together????
????????Stack<Integer>?result;
????????//trim?right?and?add
????????result?=?trimRightAdd(v);
????????StringBuffer?sb?=?new?StringBuffer();
????????try{
?????????while(true)
?????????????sb.append(result.pop());
????????}catch(Exception?e){
????????????//pass,ignore.
????????}
????????return?sb.toString();????
????}????
????????
????private?Stack<Integer>?trimRightAdd(Vector<Integer[]>?params){????
????????Stack<Integer>?result?=?new?Stack<Integer>();
????????int?carry?=?0;
????????int?maxBit?=?0;
????????
????????//todo:maxbit
????????for(Integer[]?i?:?params){
????????????int?il?=?i.length;
????????????maxBit?=?il?>?maxBit?il:maxBit;
????????}
????????//bit?moving?,?from?low?to?higth
????????int?indexDecreaseCount?=?1;
????????int?columnValue?=?0;
????????int?bitValue?=?0;????
????????for(int?k?=?0?;?k?<?maxBit;?k++){
?????????if(k?>?0){
?????????????result.push(bitValue);
?????????????columnValue?=?0;
?????????????bitValue?=?0;
?????????}
?????????//value?of?each?column,including?carry????
?????????int?num?=?0;
?????????for(Integer[]?param?:?params){
???????????????int?index?=?param.length?-?indexDecreaseCount;
?????????????try{
?????????????????num?=?param[index];
?????????????}catch(Exception?e){
?????????????????num?=?0;
?????????????}
?????????????//TODO:?may?be?simulation?calculate?is?better?here
?????????????columnValue?+=?num;
?????????}
?????????//first?bit
?????????if(k?!=?maxBit-1?){
?????????????columnValue?+=?carry;
?????????????carry?=?(int)(columnValue/10);
?????????????bitValue?=?columnValue?-?(?10?*?carry?);
?????????????indexDecreaseCount?++;
?????????}else{
?????????????columnValue?+=?carry;
?????????????result.push(columnValue);
?????????}
???????}
???????return?result;
????}????
????
}測試計算結果
package?s1;
public?class?Demo{
????
????private?TwoNumberOperation?operatorMultiply?=?new?BigNumberMultiply();
????
????public?void?multiplyDemo(String?param1,String?param2){
????????String?result?=?operatorMultiply.calculate(param1,param2);
????????System.out.println?(param1+"?x?"+param2+"?=?"+result);
????}
????
????public?static?void?main?(String[]?args)?{
????????Demo?demo?=?new?Demo();
????????demo.multiplyDemo("12","12");
????????demo.multiplyDemo("56","67");
????????demo.multiplyDemo("3459398","11667278");
????????demo.multiplyDemo("9283736253829832323432342342543654576343534564353734534534534534534553773453453453453453455377345345345345345345537734534534534534534553773453453453453453455377345345345345345345537734534534534534534553745645545",
??????????????????????????"23470926947345345345345345345537734534534534534534553773453453453453453455377345345345345345345537734534534534534534553773453453453453453455377345345345345345345537734534534534534534553773453453453453453455377345345345345345345537863053758734076407083760987207345345345345345345537693709479");
????}
????
}
--------------------Configuration: <Default>--------------------
12 x 12 = 144
56 x 67 = 3752
3459398 x 11667278 = 40361758178644
9283736253829832323432342342543654576343534564353734534534534534534553773453453453453453455377345345345345345345537734534534534534534553773453453453453453455377345345345345345345537734534534534534534553745645545 x 23470926947345345345345345345537734534534534534534553773453453453453453455377345345345345345345537734534534534534534553773453453453453453455377345345345345345345537734534534534534534553773453453453453453455377345345345345345345537863053758734076407083760987207345345345345345345537693709479 = 217897895412061538535213749538424917178427642790309526149197050342787946552594940694811082625513148107368458788645637103672066743646902872289253339664141494118086813947265391829794894470256056436951017797373234350763998817946444452982381515332165838866556971112151531240855136817304521889160157930869290050844235614446072972714978233006835557537630008993034139267140464023218920328137852716504553853724234899138660678581541565601300563516326950021051186577024411324340905167953542819936071934540621055
Process completed.