秋招感谢信收割机:private static int dfs(final String str, final int len, final long sum) {
if (len == 1) {
return sum - Long.valueOf(str.substring(0)) == 0 ? 1 : 0;
}
final long val = Long.valueOf(str.substring(len - 1));
final int noRes = dfs(str, len - 1, sum);
final int addRes = dfs(str.substring(0, len - 1), len - 1, sum - val);
final int minusRes = dfs(str.substring(0, len - 1), len - 1, sum + val);
return addRes + minusRes + noRes;
}