LeetCode 784. Letter Case Permutation (字母大小写全排列 )
题目标签:Backtracking
用dfs,只对字母分别递归小写 和 大写,具体看code。
Java Solution:
Runtime: 1 ms, faster than 100.00 %
Memory Usage: 42.7 MB, less than 8.00 %
完成日期:12/15/2019
关键点:dfs
class Solution { public List<String> letterCasePermutation(String S) { List<String> result = new ArrayList<>(); DFS(result, S.toCharArray(), 0); return result; } private void DFS(List<String> res, char [] cArr, int pos) { if(pos == cArr.length) { res.add(new String(cArr)); return; } if(Character.isLetter(cArr[pos])) { // lower case cArr[pos] = Character.toLowerCase(cArr[pos]); DFS(res, cArr, pos+1); // upper case cArr[pos] = Character.toUpperCase(cArr[pos]); DFS(res, cArr, pos+1); } else { DFS(res, cArr, pos+1); } } }
参考资料:n/a
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