傻傻然：用dfs，先发m拆分放进list里面，递归时候再取出来 public class findMax { int max; public int findMaxNumber(int m , int n) { max = 0; List<Integer> list = new LinkedList<>(); while (m > 0) { list.add(0,m%10); m = m/10; } getMax(list,0,n,0); return 0; } private void getMax(List<Integer> list, int i, int n, int sum) { if (sum > max && i == list.size()) { max = sum; } for (int j = i; j < list.size(); j++) { int a = 0; for (int k = i; k <= j; k++) { a = a*10 + list.get(k); } if (sum + a > n) { break; } getMax(list, j+1, n, sum+a); } } } /* 输入： 654122 111 输出： 110  */