package q97

func isInterleave(s1 string, s2 string, s3 string) bool {
	if len(s1)+len(s2) != len(s3) {
		return false
	}

	possible := make([][]bool, len(s1)+1)
	for i := range possible {
		possible[i] = make([]bool, len(s2)+1)
	}
	possible[0][0] = true

	for tLen := 1; tLen <= len(s3); tLen++ {
		c := s3[tLen-1]
		for len1 := max(0, tLen-len(s2)); len1 <= min(len(s1), tLen); len1++ {
			len2 := tLen - len1

			if len1 > 0 && s1[len1-1] == c && possible[len1-1][len2] {
				possible[len1][len2] = true
				continue
			}
			if len2 > 0 && s2[len2-1] == c && possible[len1][len2-1] {
				possible[len1][len2] = true
			}
		}
	}

	return possible[len(s1)][len(s2)]
}

var _ = isInterleave