题目：

题解：

func isSubsequence(s string, t string) bool {n, m := len(s), len(t)f := make([][26]int, m + 1)for i := 0; i < 26; i++ {f[m][i] = m}for i := m - 1; i >= 0; i-- {for j := 0; j < 26; j++ {if t[i] == byte(j + 'a') {f[i][j] = i} else {f[i][j] = f[i + 1][j]}}}add := 0for i := 0; i < n; i++ {if f[add][int(s[i] - 'a')] == m {return false}add = f[add][int(s[i] - 'a')] + 1}return true
}