Given two non-empty strings _A_ and _B_ composed of lowercase Latin letters, what is the minimum number of substrings of _A_ needed to form string _B_? The lengths of _A_ and _B_ are at most 100000. If the task is not possible for a given input, output a rogue value (a.k.a. -1).↵
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I was thinking about solving this with an O(N^2) DP method, but that does not fit into the time limit of 5 seconds.↵
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Please help, and thanks in advance!↵
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EDIT: Note that chosen substrings can overlap. I put some cases below.↵
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Input #1:↵
abcbcd↵
abcd↵
↵
Output #1:↵
2↵
↵
Input #2:↵
iamsmart↵
iamdumb↵
↵
Output #2:↵
-1↵
↵
Input #3:↵
asmallmallinmalta↵
atallmallinlima↵
↵
Output #3:↵
5↵
↵
Explanations: "abcd" = "ab" + "cd", no "d"s in the first string of Input 2, "atallmallinlima" = "a" + "ta" + "llmallin" + "li" + "ma"
↵
I was thinking about solving this with an O(N^2) DP method, but that does not fit into the time limit of 5 seconds.↵
↵
Please help, and thanks in advance!↵
↵
EDIT: Note that chosen substrings can overlap. I put some cases below.↵
↵
Input #1:↵
abcbcd↵
abcd↵
↵
Output #1:↵
2↵
↵
Input #2:↵
iamsmart↵
iamdumb↵
↵
Output #2:↵
-1↵
↵
Input #3:↵
asmallmallinmalta↵
atallmallinlima↵
↵
Output #3:↵
5↵
↵
Explanations: "abcd" = "ab" + "cd", no "d"s in the first string of Input 2, "atallmallinlima" = "a" + "ta" + "llmallin" + "li" + "ma"
