[LeetCode] 系统刷题3_排列组合/backtracking

 适用范围：

• 几乎所有搜索问题
• 什么时候输出
• 哪些情况需要跳过

Python library

 import itertools

itertools.product('ABC', repeat = 2)        3 * 3 = 9

list(itertools.product('ABC', repeat = 2))=> [('A', 'A'), ('A', 'B'), ('A', 'C'), ('B', 'A'), ('B', 'B'), ('B', 'C'), ('C', 'A'), ('C', 'B'), ('C', 'C')]

itertools.permutations('ABC', 2)       3 * 2 = 6

print(list(itertools.permutations('ABC', 2)))  =>   [('A', 'B'), ('A', 'C'), ('B', 'A'), ('B', 'C'), ('C', 'A'), ('C', 'B')]

itertools.combinations('ABC', 2)       3 

print(list(itertools.combinations('ABC', 2))) =>  [('A', 'B'), ('A', 'C'), ('B', 'C')]

 

相关题目：

Subsets/Combinations:

• [LeetCode] 78. Subsets tag: backtracking
• [LeetCode] 90.Subsets II tag: backtracking
• [LeetCode] 491. Increasing Subsequences_Medium tag: backtracking
• [LeetCode] 131. Palindrome Partitioning_Medium tag: DFS, backtracking, Palindrome
• [LeetCode] 40. Combination Sum II tag: backtracking
  
• [LeetCode] 39. Combination Sum_Medium tag: backtracking
• [LeetCode] 93. Restore IP Addresses_Medium tag: backtracking
• [LeetCode] 784. Letter Case Permutation_Medium tag: backtracking
• [LeetCode] 812. Largest Triangle Area_Easy tag: math
• [LeetCode] 22. Generate Parentheses_Medium tag: backtracking

 

Permutations:

• [LeetCode] 46. Permutations_Medium tag: DFS, backtracking
• [LeetCode] 47. Permutations II_Medium tag: DFS, backtracking
• [LeetCode] 51. N-Queens_Hard tag: DFS, backtracking
• [LeetCode] 52. N-QueensII_Hard tag: DFS, backtracking
• [LeetCode] 17. Letter Combinations of a Phone Number_Medium tag: backtracking

 

Backtracking

• [LeetCode] 10. Regular Expression Matching_Hard tag: backtracking, DP
• [LeetCode] 37. Sudoku Solver_Hard tag: BackTracking
• [LeetCode] 77. Combinations_Medium tag: backtracking
•  [LeetCode] 79. Word Search_Medium tag: Backtracking, DFS
• [LeetCode] 489. Robot Room Cleaner_Hard tag: DFS, backtracking