九个数字

/** * 九个数字： * 功能：实现填充。一个四位数乘以一个一位数，得到一个四位数。这九个数分别用1~9这九个数填充。 */public class NineNumbers{public static void main(String[] args){int product = 0; for(int i = 1234; i <= 9876; i++){if(!theThouthandNumberWithoutSameNumberAndZero(i)){continue;}for(int j = 1; j <= 9; j++){if(theThouthandNumberWithTheOne(i, j)){continue;}product = i * j;if(!isThouthandNumber(product)){continue;}if(!theThouthandNumberWithoutSameNumberAndZero(product)){continue;} if(theThouthandNumberWithTheOne(product, j)){continue;}if(theTwoThouthandNumberWithoutSameNumber(i, product)){System.out.println("^_^ : I know " + i + " * " + j + " = " + product);}}}}/** * 判断一个数是不是一个四位数 */public static boolean isThouthandNumber(int number){int thouthand = number/1000;if(thouthand > 9 || thouthand < 1){return false;}return true;}/** * 判断四位数里面有没有跟一个一位数相同的数字 */public static boolean theThouthandNumberWithTheOne(int thoutandNumber, int one){int number_thousand = thoutandNumber/1000;int number_hundred = thoutandNumber%1000/100;int number_ten = thoutandNumber%100/10;int number_one = thoutandNumber%10;if(one == number_thousand || one == number_hundred || one == number_ten || one == number_one){return true;}return false;}/** * 判断两个四位数不含有相同的数字 */public static boolean theTwoThouthandNumberWithoutSameNumber(int number1, int number2){int number1_thousand = number1/1000;int number1_hundred = number1%1000/100;int number1_ten = number1%100/10;int number1_one = number1%10;int number2_thousand = number2/1000;int number2_hundred = number2%1000/100;int number2_ten = number2%100/10;int number2_one = number2%10;boolean[] signs = new boolean[10];signs[number1_thousand] = true;signs[number1_hundred] = true;signs[number1_ten] = true;signs[number1_one] = true;if(signs[number2_thousand]){return false;} if(signs[number2_hundred]){return false;} if(signs[number2_ten]){return false;}if(signs[number2_one]){return false;} return true;}/** * 判断一个四位数没有相同数字且不含有零 */public static boolean theThouthandNumberWithoutSameNumberAndZero(int number){int number_thousand = number/1000;int number_hundred = number%1000/100;int number_ten = number%100/10;int number_one = number%10;boolean[] signs = new boolean[10];signs[number_thousand] = true;if(!signs[number_hundred]){signs[number_hundred] = true;} else {return false;}if(!signs[number_ten]){signs[number_ten] = true;} else {return false;}if(!signs[number_one]){signs[number_one] = true;} else {return false;}if(signs[0]){return false;}return true;}}