87. Scramble String
If we have the split point, s1 starting point and s2 starting point, we can decide the state
We create a table dp[len][i][j] which indicate S1[i...i + len - 1] is scrambled of S2[j...j + len - 1]
S1[i...i + len - 1]
S2[j...j + len - 1]
Solution