Basics

• 注意输入本身有没有duplicates.
• 用 prev 记录位置 in for loop
  • 放回抽样 dfs(... i)
  • 不放回抽样 dfs(... i+1)
• for loop 起始 根据搜索树展开
  • e.g. permutation: i = 0 -> array length
  • e.g. subsets: i = prev -> array length
• O(number of solutions * complexity for each solution)

Problems

Permutations: http://www.lintcode.com/en/problem/permutations/#

Permutations ii: http://www.lintcode.com/en/problem/permutations-ii/

Combination: http://www.lintcode.com/en/problem/combinations/

Subsets: http://www.lintcode.com/en/problem/subsets/

Subsets ii - with dup: https://leetcode.com/problems/subsets-ii/#/description

Combination Sum: http://www.lintcode.com/en/problem/combination-sum/#

Combination Sum ii: http://www.lintcode.com/en/problem/combination-sum-ii/#

Combination Sum iii: https://leetcode.com/problems/combination-sum-iii/#/description

Combination Sum IV: https://leetcode.com/problems/combination-sum-iv/#/description

Valid Sudoku: http://www.lintcode.com/en/problem/valid-sudoku/

Sudoku Solver: https://leetcode.com/problems/sudoku-solver/description/

palindrome partitioning: http://www.lintcode.com/en/problem/palindrome-partitioning/

word ladder: http://www.lintcode.com/en/problem/word-ladder/

word ladder ii: http://www.lintcode.com/en/problem/word-ladder-ii/

generate parentheses: https://leetcode.com/problems/generate-parentheses/description/

restore IP addresses: http://lintcode.com/en/problem/restore-ip-addresses/

palindrome partitioning: http://lintcode.com/en/problem/palindrome-partitioning/

letter combinations of a phone number: http://lintcode.com/en/problem/letter-combinations-of-a-phone-number/

combination sum iv: https://leetcode.com/problems/combination-sum-iv/description/

word search: http://lintcode.com/en/problem/word-search/

word search ii (Trie)

number of islands: https://leetcode.com/problems/number-of-islands/description/

n queens: https://leetcode.com/problems/n-queens/description/

n queens ii: https://leetcode.com/problems/n-queens/description/