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| -rw-r--r-- | README.md | 2 | ||||
| -rw-r--r-- | ch03/3_b_5.hs | 22 |
2 files changed, 23 insertions, 1 deletions
@@ -57,7 +57,7 @@ more visible in the list the first exercise of a group is in bold italics. | 3_b_2 | yes, in 3_b_1 | | | | 3_b_3 | yes | | | | 3_b_4 | yes | | | -| 3_b_5 | | | | +| 3_b_5 | yes | | | | 3_b_6 | | 70 | | | 3_b_7 | | | | | 3_b_8 | | | | diff --git a/ch03/3_b_5.hs b/ch03/3_b_5.hs new file mode 100644 index 0000000..5bc89aa --- /dev/null +++ b/ch03/3_b_5.hs @@ -0,0 +1,22 @@ +-- Write a function that determines whether its input list is a palindrome. + +reverseList [] = [] +reverseList (x:xs) = (reverseList xs) ++ [x] + +isPalindrome xs = xs == (reverseList xs) + +-- ghci> :l 3_b_5.hs +-- [1 of 1] Compiling Main ( 3_b_5.hs, interpreted ) +-- Ok, one module loaded. +-- ghci> isPalindrome [] +-- True +-- ghci> isPalindrome [1] +-- True +-- ghci> isPalindrome [1, 2] +-- False +-- ghci> isPalindrome [1, 2, 1] +-- True +-- ghci> isPalindrome [1, 2, 2, 1] +-- True +-- ghci> isPalindrome [1, 2, 3, 2, 4] +-- False |