In this case, both the length and index values are zero, so they match.

在本例中，长度和索引值都为0，所以它们是匹配的。

youdao

The base case is whenever S1 or S2 is a zero-length string.

（基线条件（basecase）是S1或S2为长度为零的字符串的情形。

youdao

For each test case, print the length of the longest road on a single line.

求图中的一条最长路径，又是回溯。

youdao

For each test case, print the length of the longest road on a single line.

求图中的一条最长路径，又是回溯。

youdao