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6.1 KiB
6.1 KiB
| title | type |
|---|---|
| Backtracking | docs |
Backtracking
- 排列问题 Permutations。第 46 题，第 47 题。第 60 题，第 526 题，第 996 题。
- 组合问题 Combination。第 39 题，第 40 题，第 77 题，第 216 题。
- 排列和组合杂交问题。第 1079 题。
- N 皇后终极解法(二进制解法)。第 51 题，第 52 题。
- 数独问题。第 37 题。
- 四个方向搜索。第 79 题，第 212 题，第 980 题。
- 子集合问题。第 78 题，第 90 题。
- Trie。第 208 题，第 211 题。
- BFS 优化。第 126 题，第 127 题。
- DFS 模板。(只是一个例子，不对应任何题)
func combinationSum2(candidates []int, target int) [][]int {
if len(candidates) == 0 {
return [][]int{}
}
c, res := []int{}, [][]int{}
sort.Ints(candidates)
findcombinationSum2(candidates, target, 0, c, &res)
return res
}
func findcombinationSum2(nums []int, target, index int, c []int, res *[][]int) {
if target == 0 {
b := make([]int, len(c))
copy(b, c)
*res = append(*res, b)
return
}
for i := index; i < len(nums); i++ {
if i > index && nums[i] == nums[i-1] { // 这里是去重的关键逻辑
continue
}
if target >= nums[i] {
c = append(c, nums[i])
findcombinationSum2(nums, target-nums[i], i+1, c, res)
c = c[:len(c)-1]
}
}
}
- BFS 模板。(只是一个例子，不对应任何题)
func updateMatrix_BFS(matrix [][]int) [][]int {
res := make([][]int, len(matrix))
if len(matrix) == 0 || len(matrix[0]) == 0 {
return res
}
queue := make([][]int, 0)
for i, _ := range matrix {
res[i] = make([]int, len(matrix[0]))
for j, _ := range res[i] {
if matrix[i][j] == 0 {
res[i][j] = -1
queue = append(queue, []int{i, j})
}
}
}
level := 1
for len(queue) > 0 {
size := len(queue)
for size > 0 {
size -= 1
node := queue[0]
queue = queue[1:]
i, j := node[0], node[1]
for _, direction := range [][]int{{-1, 0}, {1, 0}, {0, 1}, {0, -1}} {
x := i + direction[0]
y := j + direction[1]
if x < 0 || x >= len(matrix) || y < 0 || y >= len(matrix[0]) || res[x][y] < 0 || res[x][y] > 0 {
continue
}
res[x][y] = level
queue = append(queue, []int{x, y})
}
}
level++
}
for i, row := range res {
for j, cell := range row {
if cell == -1 {
res[i][j] = 0
}
}
}
return res
}
| Title | Solution | Difficulty | Time | Space | 收藏 |
|---|---|---|---|---|---|
| 17. Letter Combinations of a Phone Number | [Go]({{< relref "/ChapterFour/0017.Letter-Combinations-of-a-Phone-Number.md" >}}) | Medium | O(log n) | O(1) | |
| 22. Generate Parentheses | [Go]({{< relref "/ChapterFour/0022.Generate-Parentheses.md" >}}) | Medium | O(log n) | O(1) | |
| 37. Sudoku Solver | [Go]({{< relref "/ChapterFour/0037.Sudoku-Solver.md" >}}) | Hard | O(n^2) | O(n^2) | ❤️ |
| 39. Combination Sum | [Go]({{< relref "/ChapterFour/0039.Combination-Sum.md" >}}) | Medium | O(n log n) | O(n) | |
| 40. Combination Sum II | [Go]({{< relref "/ChapterFour/0040.Combination-Sum-II.md" >}}) | Medium | O(n log n) | O(n) | |
| 46. Permutations | [Go]({{< relref "/ChapterFour/0046.Permutations.md" >}}) | Medium | O(n) | O(n) | ❤️ |
| 47. Permutations II | [Go]({{< relref "/ChapterFour/0047.Permutations-II.md" >}}) | Medium | O(n^2) | O(n) | ❤️ |
| 51. N-Queens | [Go]({{< relref "/ChapterFour/0051.N-Queens.md" >}}) | Hard | O(n^2) | O(n) | ❤️ |
| 52. N-Queens II | [Go]({{< relref "/ChapterFour/0052.N-Queens-II.md" >}}) | Hard | O(n^2) | O(n) | ❤️ |
| 60. Permutation Sequence | [Go]({{< relref "/ChapterFour/0060.Permutation-Sequence.md" >}}) | Medium | O(n log n) | O(1) | |
| 77. Combinations | [Go]({{< relref "/ChapterFour/0077.Combinations.md" >}}) | Medium | O(n) | O(n) | ❤️ |
| 78. Subsets | [Go]({{< relref "/ChapterFour/0078.Subsets.md" >}}) | Medium | O(n^2) | O(n) | ❤️ |
| 79. Word Search | [Go]({{< relref "/ChapterFour/0079.Word-Search.md" >}}) | Medium | O(n^2) | O(n^2) | ❤️ |
| 89. Gray Codes | [Go]({{< relref "/ChapterFour/0089.Gray-Code.md" >}}) | Medium | O(n) | O(1) | |
| 90. Subsets II | [Go]({{< relref "/ChapterFour/0090.Subsets-II.md" >}}) | Medium | O(n^2) | O(n) | ❤️ |
| 93. Restore IP Addresses | [Go]({{< relref "/ChapterFour/0093.Restore-IP-Addresses.md" >}}) | Medium | O(n) | O(n) | ❤️ |
| 126. Word Ladder II | [Go]({{< relref "/ChapterFour/0126.Word-Ladder-II.md" >}}) | Hard | O(n) | O(n^2) | ❤️ |
| 131. Palindrome Partitioning | [Go]({{< relref "/ChapterFour/0131.Palindrome-Partitioning.md" >}}) | Medium | O(n) | O(n^2) | ❤️ |
| 211. Add and Search Word - Data structure design | [Go]({{< relref "/ChapterFour/0211.Add-and-Search-Word---Data-structure-design.md" >}}) | Medium | O(n) | O(n) | ❤️ |
| 212. Word Search II | [Go]({{< relref "/ChapterFour/0212.Word-Search-II.md" >}}) | Hard | O(n^2) | O(n^2) | ❤️ |
| 216. Combination Sum III | [Go]({{< relref "/ChapterFour/0216.Combination-Sum-III.md" >}}) | Medium | O(n) | O(1) | ❤️ |
| 306. Additive Number | [Go]({{< relref "/ChapterFour/0306.Additive-Number.md" >}}) | Medium | O(n^2) | O(1) | ❤️ |
| 357. Count Numbers with Unique Digits | [Go]({{< relref "/ChapterFour/0357.Count-Numbers-with-Unique-Digits.md" >}}) | Medium | O(1) | O(1) | |
| 401. Binary Watch | [Go]({{< relref "/ChapterFour/0401.Binary-Watch.md" >}}) | Easy | O(1) | O(1) | |
| 526. Beautiful Arrangement | [Go]({{< relref "/ChapterFour/0526.Beautiful-Arrangement.md" >}}) | Medium | O(n^2) | O(1) | ❤️ |
| 784. Letter Case Permutation | [Go]({{< relref "/ChapterFour/0784.Letter-Case-Permutation.md" >}}) | Easy | O(n) | O(n) | |
| 842. Split Array into Fibonacci Sequence | [Go]({{< relref "/ChapterFour/0842.Split-Array-into-Fibonacci-Sequence.md" >}}) | Medium | O(n^2) | O(1) | ❤️ |
| 980. Unique Paths III | [Go]({{< relref "/ChapterFour/0980.Unique-Paths-III.md" >}}) | Hard | O(n log n) | O(n) | |
| 996. Number of Squareful Arrays | [Go]({{< relref "/ChapterFour/0996.Number-of-Squareful-Arrays.md" >}}) | Hard | O(n log n) | O(n) | |
| 1079. Letter Tile Possibilities | [Go]({{< relref "/ChapterFour/1079.Letter-Tile-Possibilities.md" >}}) | Medium | O(n^2) | O(1) | ❤️ |
| --------------------------------------- | --------------------------------- | -------------------------- | ----------------------- | ----------- | -------- |