Combination Sum, Combination Sum II

Author: idf

336 Palindrome Pairs.py

@@ -55,20 +55,20 @@ def palindromePairs(self, words: List[str]) -> List[List[int]]:
         for idx, w in enumerate(words):
             cur = root
             for i in range(len(w) - 1, -1, -1):
-                #  cur.children[w[i]]  # error, pre-forward unable to handle empty str
-                if self.is_palindrome(w, 0, i + 1):  # exclude w[i] rather than include
+                #  cur.children[w[i]]  # error, pre-advancing the trie is unable to handle empty str
+                if self.is_palindrome(w, 0, i + 1):
                     cur.pali_prefix_idxes.append(idx)
 
                 cur = cur.children[w[i]]
 
-            cur.pali_prefix_idxes.append(idx)
+            cur.pali_prefix_idxes.append(idx)  # empty str is palindrome
             cur.word_idx = idx  # word ends
 
         ret = []
         for idx, w in enumerate(words):
             cur = root
             for i in range(len(w)):
-                # cur.children.get(w[i], None)  # error, pre-forward unable to handle empty str
+                # cur.children.get(w[i], None)  # error, pre-advancing the trie is unable to handle empty str
                 if self.is_palindrome(w, i, len(w)) and cur.word_idx is not None and cur.word_idx != idx:
                     ret.append([idx, cur.word_idx])
 

759 Employee Free Time.py

@@ -60,7 +60,7 @@ def employeeFreeTime(self, schedule: List[List[List[int]]]) -> List[List[int]]:
 
         Similar to meeting rooms II
         """
-        max_end = min(
+        cur_max_end = min(
             itv[E]
             for itvs in schedule
             for itv in itvs
@@ -76,10 +76,10 @@ def employeeFreeTime(self, schedule: List[List[List[int]]]) -> List[List[int]]:
         while q:
             _, i, j = heapq.heappop(q)
             itv = schedule[i][j]
-            if max_end < itv[S]:
-                ret.append([max_end, itv[S]])
+            if cur_max_end < itv[S]:
+                ret.append([cur_max_end, itv[S]])
 
-            max_end = max(max_end, itv[E])
+            cur_max_end = max(cur_max_end, itv[E])
 
             # next
             j += 1
@@ -122,7 +122,7 @@ def employeeFreeTime_error(self, schedule: List[List[List[int]]]) -> List[List[i
         use index instead
         """
         schedules = list(map(iter, schedule))
-        max_end = min(
+        cur_max_end = min(
             itv[E]
             for emp in schedule
             for itv in emp
@@ -136,9 +136,9 @@ def employeeFreeTime_error(self, schedule: List[List[List[int]]]) -> List[List[i
         ret = []
         while q:
             _, itv, emp_iter = heapq.heappop(q)
-            if max_end < itv[S]:
-                ret.append([max_end, itv[S]])
-            max_end = max(max_end, itv[E])
+            if cur_max_end < itv[S]:
+                ret.append([cur_max_end, itv[S]])
+            cur_max_end = max(cur_max_end, itv[E])
             itv = next(emp_iter, None)
             if itv:
                 heapq.heappush(q, (itv[S], itv, emp_iter))