Python: Can print answer but cannot return answer (Palindrome Partitioning) -

Python: Can print answer but cannot return answer (Palindrome Partitioning) -

in python code below, when input s = "ab", [[]] should [["a","b"]]. have checked 2 functions individually , turned out right. can print out reply [["a","b"]] in line 26, cannot reply return. quite confused here , appreciate ideas can help.

class solution: # @param s, string # @return list of lists of string def partition(self, s): ############### depth first search: utilize recursion a!!! if s == "": homecoming [[]] if len(s) == 1: homecoming [[s[0]]] self.result = [] temp = [] stack = [] # stack 2d lists k in range(len(s)): stack.append([]) in range(len(s)): j in range(i+1,len(s)+1): substr = s[i:j] if substr == substr[::-1]: stack[i].append(s[i:j]) self.dfs(temp, stack, 0, len(s)) homecoming self.result def dfs(self, temp, stack, start, end): if start == end: self.result.append(temp) print(self.result) homecoming else: in range(len(stack[start])): temp.append(stack[start][i]) self.dfs(temp, stack, start+len(stack[start][i]), end) temp.pop()

you sharing temp between recursive calls:

temp.append(stack[start][i]) self.dfs(temp, stack, start+len(stack[start][i]), end) temp.pop()

the list object referenced temp appended self.result:

if start == end: self.result.append(temp)

but empty shared list object 1 time again popping after returning. removes elements shared list object after printed.

you want append copy instead:

if start == end: self.result.append(temp[:])

you don't need temp. build new lists instead:

for item in stack[start]: self.dfs([item], stack, start + len(item), end)

you never more add together 1 item temp, remove again; starting empty temp list means can build new list objects recursive calls.

instead of looping on range() indexing, loop on stack[start] directly.

python