使用Stack来完成:
代码如下:
package ca.map; import java.util.Stack; public class Sum1_19eq20 { //算法: 求1至19这些自然数数中,所有相加为20的组合 public static void main(String[] args) { combinateDataOfRange(1, 19, 20); } public static void combinateDataOfRange(int min,int max,int target){ combinateData(0, min, max, target, new Stack<Integer>()); } public static void combinateData(int sum,int min,int max,int target,Stack<Integer> stack){ for(int i = stack.isEmpty() ? min : (Integer)stack.lastElement() + 1;i < max;++i){ int tempSum = sum + i; stack.push(i); if(tempSum == target){ System.out.println(stack+"="+target); }else{ combinateData(tempSum, min, max, target, stack); } stack.pop(); } } }
输出为:
[1, 2, 3, 4, 10]=20
[1, 2, 3, 5, 9]=20
[1, 2, 3, 6, 8]=20
[1, 2, 3, 14]=20
[1, 2, 4, 5, 8]=20
[1, 2, 4, 6, 7]=20
[1, 2, 4, 13]=20
[1, 2, 5, 12]=20
[1, 2, 6, 11]=20
[1, 2, 7, 10]=20
[1, 2, 8, 9]=20
[1, 2, 17]=20
[1, 3, 4, 5, 7]=20
[1, 3, 4, 12]=20
[1, 3, 5, 11]=20
[1, 3, 6, 10]=20
[1, 3, 7, 9]=20
[1, 3, 16]=20
[1, 4, 5, 10]=20
[1, 4, 6, 9]=20
[1, 4, 7, 8]=20
[1, 4, 15]=20
[1, 5, 6, 8]=20
[1, 5, 14]=20
[1, 6, 13]=20
[1, 7, 12]=20
[1, 8, 11]=20
[1, 9, 10]=20
[2, 3, 4, 5, 6]=20
[2, 3, 4, 11]=20
[2, 3, 5, 10]=20
[2, 3, 6, 9]=20
[2, 3, 7, 8]=20
[2, 3, 15]=20
[2, 4, 5, 9]=20
[2, 4, 6, 8]=20
[2, 4, 14]=20
[2, 5, 6, 7]=20
[2, 5, 13]=20
[2, 6, 12]=20
[2, 7, 11]=20
[2, 8, 10]=20
[2, 18]=20
[3, 4, 5, 8]=20
[3, 4, 6, 7]=20
[3, 4, 13]=20
[3, 5, 12]=20
[3, 6, 11]=20
[3, 7, 10]=20
[3, 8, 9]=20
[3, 17]=20
[4, 5, 11]=20
[4, 6, 10]=20
[4, 7, 9]=20
[4, 16]=20
[5, 6, 9]=20
[5, 7, 8]=20
[5, 15]=20
[6, 14]=20
[7, 13]=20
[8, 12]=20
[9, 11]=20