Group Shifted Strings
Given a string, we can "shift" each of its letter to its successive letter, for example:"abc" -> "bcd". We can keep "shifting" which forms the sequence:
"abc" -> "bcd" -> ... -> "xyz"Given a list of strings which contains only lowercase alphabets, group all strings that belong to the same shifting sequence.
Example:
Input: ["abc", "bcd", "acef", "xyz", "az", "ba", "a", "z"],
Output:
[
["abc","bcd","xyz"],
["az","ba"],
["acef"],
["a","z"]
]Here is a solution.
class Solution {
public List<List<String>> groupStrings(String[] strings) {
Map<String, List<String>> map = new HashMap<>();
for (String s : strings) {
StringBuilder sb = new StringBuilder();
char[] chars = s.toCharArray();
int shift = 'z' - chars[0];
System.out.println("Shift: " + shift);
for (char c : chars) {
System.out.println("Letter: " + (int) c);
int normalized = (c + shift) % 26;
System.out.println("Normalized: " + normalized);
sb.append(normalized);
}
String key = sb.toString();
System.out.println("Key: " + key);
List<String> list = map.getOrDefault(key, new ArrayList<>());
list.add(s);
map.put(key, list);
System.out.println();
}
return new ArrayList<>(map.values());
}
}Here is the output for better understanding what is happening (how shifting is done and how to normalize it).
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