From d402811c9a1837bb33753b158602f80ab296cd01 Mon Sep 17 00:00:00 2001 From: yanglbme Date: Wed, 8 Sep 2021 17:32:41 +0800 Subject: [PATCH] feat: add solutions to lcs problems 02,03 --- index.html | 2 +- lcs/LCS 02. 完成一半题目/README.md | 37 ++++++- lcs/LCS 02. 完成一半题目/Solution.java | 19 ++++ lcs/LCS 02. 完成一半题目/Solution.py | 12 +++ lcs/LCS 03. 主题空间/README.md | 135 ++++++++++++++++++++++++- lcs/LCS 03. 主题空间/Solution.java | 44 ++++++++ lcs/LCS 03. 主题空间/Solution.py | 28 +++++ 7 files changed, 272 insertions(+), 5 deletions(-) create mode 100644 lcs/LCS 02. 完成一半题目/Solution.java create mode 100644 lcs/LCS 02. 完成一半题目/Solution.py create mode 100644 lcs/LCS 03. 主题空间/Solution.java create mode 100644 lcs/LCS 03. 主题空间/Solution.py diff --git a/index.html b/index.html index b4c59b69f3..9393b914db 100644 --- a/index.html +++ b/index.html @@ -28,7 +28,7 @@ name: 'leetcode', logo: '/images/doocs-leetcode.png', search: [ - '/', '/solution/', '/lcof/', '/lcof2/', '/lcci/', '/lcs', 'lcp', '/basic/' + '/', '/solution/', '/lcof/', '/lcof2/', '/lcci/', '/lcs/', '/lcp/', '/basic/' ], loadSidebar: 'summary.md', auto2top: true, diff --git a/lcs/LCS 02. 完成一半题目/README.md b/lcs/LCS 02. 完成一半题目/README.md index 0fda6ffb28..010da7a217 100644 --- a/lcs/LCS 02. 完成一半题目/README.md +++ b/lcs/LCS 02. 完成一半题目/README.md @@ -36,6 +36,10 @@ +统计各个问题类型出现的次数，按照次数降序排列。 + +然后依次选择问题类型，直至满足条件。 + ### **Python3** @@ -43,7 +47,18 @@ ```python - +class Solution: + def halfQuestions(self, questions: List[int]) -> int: + counter = collections.Counter(questions) + counter = OrderedDict(counter.most_common()) + n = len(questions) >> 1 + res = 0 + for _, v in counter.items(): + res += 1 + if v >= n: + return res + n -= v + return res ``` ### **Java** @@ -51,7 +66,25 @@ ```java - +class Solution { + public int halfQuestions(int[] questions) { + int[] counter = new int[1010]; + for (int e : questions) { + ++counter[e]; + } + int n = questions.length >> 1; + Arrays.sort(counter); + int res = 0; + for (int i = counter.length - 1; i >= 0; --i) { + ++res; + if (counter[i] >= n) { + return res; + } + n -= counter[i]; + } + return res; + } +} ``` ### **...** diff --git a/lcs/LCS 02. 完成一半题目/Solution.java b/lcs/LCS 02. 完成一半题目/Solution.java new file mode 100644 index 0000000000..740b20be0a --- /dev/null +++ b/lcs/LCS 02. 完成一半题目/Solution.java @@ -0,0 +1,19 @@ +class Solution { + public int halfQuestions(int[] questions) { + int[] counter = new int[1010]; + for (int e : questions) { + ++counter[e]; + } + int n = questions.length >> 1; + Arrays.sort(counter); + int res = 0; + for (int i = counter.length - 1; i >= 0; --i) { + ++res; + if (counter[i] >= n) { + return res; + } + n -= counter[i]; + } + return res; + } +} \ No newline at end of file diff --git a/lcs/LCS 02. 完成一半题目/Solution.py b/lcs/LCS 02. 完成一半题目/Solution.py new file mode 100644 index 0000000000..5f08841890 --- /dev/null +++ b/lcs/LCS 02. 完成一半题目/Solution.py @@ -0,0 +1,12 @@ +class Solution: + def halfQuestions(self, questions: List[int]) -> int: + counter = collections.Counter(questions) + counter = OrderedDict(counter.most_common()) + n = len(questions) >> 1 + res = 0 + for _, v in counter.items(): + res += 1 + if v >= n: + return res + n -= v + return res diff --git a/lcs/LCS 03. 主题空间/README.md b/lcs/LCS 03. 主题空间/README.md index 07501f35e2..889d927aba 100644 --- a/lcs/LCS 03. 主题空间/README.md +++ b/lcs/LCS 03. 主题空间/README.md @@ -15,7 +15,7 @@ > 输出：`1` > > 解释：4 个主题空间中，只有 1 个不与走廊相邻，面积为 1。 -> ![image.png](https://pic.leetcode-cn.com/1613708145-rscctN-image.png) +> ![image.png](https://cdn.jsdelivr.net/gh/doocs/leetcode@main/lcs/LCS%2003.%20主题空间/images/1613708145-rscctN-image.png) **示例 2:** @@ -24,7 +24,7 @@ > 输出：`3` > > 解释：8 个主题空间中，有 5 个不与走廊相邻，面积分别为 3、1、1、1、2，最大面积为 3。 -> ![image.png](https://cdn.jsdelivr.net/gh/doocs/leetcode@main/lcs/LCS%2003.%20主题空间/images/613707985-KJyiXJ-image.png) +> ![image.png](https://cdn.jsdelivr.net/gh/doocs/leetcode@main/lcs/LCS%2003.%20主题空间/images/1613707985-KJyiXJ-image.png) **提示：** @@ -36,6 +36,67 @@ +并查集。 + +并查集模板： + +模板 1——朴素并查集： + +```python +# 初始化，p存储每个点的父节点 +p = list(range(n)) + +# 返回x的祖宗节点 +def find(x): + if p[x] != x: + # 路径压缩 + p[x] = find(p[x]) + return p[x] + +# 合并a和b所在的两个集合 +p[find(a)] = find(b) +``` + +模板 2——维护 size 的并查集： + +```python +# 初始化，p存储每个点的父节点，size只有当节点是祖宗节点时才有意义，表示祖宗节点所在集合中，点的数量 +p = list(range(n)) +size = [1] * n + +# 返回x的祖宗节点 +def find(x): + if p[x] != x: + # 路径压缩 + p[x] = find(p[x]) + return p[x] + +# 合并a和b所在的两个集合 +if find(a) != find(b): + size[find(b)] += size[find(a)] + p[find(a)] = find(b) +``` + +模板 3——维护到祖宗节点距离的并查集： + +```python +# 初始化，p存储每个点的父节点，d[x]存储x到p[x]的距离 +p = list(range(n)) +d = [0] * n + +# 返回x的祖宗节点 +def find(x): + if p[x] != x: + t = find(p[x]) + d[x] += d[p[x]] + p[x] = t + return p[x] + +# 合并a和b所在的两个集合 +p[find(a)] = find(b) +d[find(a)] = distance +``` + ### **Python3** @@ -43,7 +104,34 @@ ```python +class Solution: + def largestArea(self, grid: List[str]) -> int: + m, n = len(grid), len(grid[0]) + p = list(range(m * n + 1)) + def find(x): + if p[x] != x: + p[x] = find(p[x]) + return p[x] + + for i in range(m): + for j in range(n): + if i == 0 or i == m - 1 or j == 0 or j == n - 1 or grid[i][j] == '0': + p[find(i * n + j)] = find(m * n) + else: + for x, y in [(-1, 0), (1, 0), (0, -1), (0, 1)]: + if grid[i + x][j + y] == '0' or grid[i][j] == grid[i + x][j + y]: + p[find(i * n + j)] = find((i + x) * n + j + y) + + mp = collections.defaultdict(int) + res = 0 + for i in range(m): + for j in range(n): + root = find(i * n + j) + if root != find(m * n): + mp[root] += 1 + res = max(res, mp[root]) + return res ``` ### **Java** @@ -51,7 +139,50 @@ ```java +class Solution { + private int[] p; + private int[][] dirs = new int[][]{{0, -1}, {0, 1}, {1, 0}, {-1, 0}}; + public int largestArea(String[] grid) { + int m = grid.length, n = grid[0].length(); + p = new int[m * n + 1]; + for (int i = 0; i < p.length; ++i) { + p[i] = i; + } + for (int i = 0; i < m; ++i) { + for (int j = 0; j < n; ++j) { + if (i == 0 || i == m - 1 || j == 0 || j == n - 1 || grid[i].charAt(j) == '0') { + p[find(i * n + j)] = find(m * n); + } else { + for (int[] e : dirs) { + if (grid[i + e[0]].charAt(j + e[1]) == '0' || grid[i].charAt(j) == grid[i + e[0]].charAt(j + e[1])) { + p[find(i * n + j)] = find((i + e[0]) * n + j + e[1]); + } + } + } + } + } + Map mp = new HashMap<>(); + int res = 0; + for (int i = 0; i < m; ++i) { + for (int j = 0; j < n; ++j) { + int root = find(i * n + j); + if (root != find(m * n)) { + mp.put(root, mp.getOrDefault(root, 0) + 1); + res = Math.max(res, mp.get(root)); + } + } + } + return res; + } + + private int find(int x) { + if (p[x] != x) { + p[x] = find(p[x]); + } + return p[x]; + } +} ``` ### **...** diff --git a/lcs/LCS 03. 主题空间/Solution.java b/lcs/LCS 03. 主题空间/Solution.java new file mode 100644 index 0000000000..1b084b0a4d --- /dev/null +++ b/lcs/LCS 03. 主题空间/Solution.java @@ -0,0 +1,44 @@ +class Solution { + private int[] p; + private int[][] dirs = new int[][]{{0, -1}, {0, 1}, {1, 0}, {-1, 0}}; + + public int largestArea(String[] grid) { + int m = grid.length, n = grid[0].length(); + p = new int[m * n + 1]; + for (int i = 0; i < p.length; ++i) { + p[i] = i; + } + for (int i = 0; i < m; ++i) { + for (int j = 0; j < n; ++j) { + if (i == 0 || i == m - 1 || j == 0 || j == n - 1 || grid[i].charAt(j) == '0') { + p[find(i * n + j)] = find(m * n); + } else { + for (int[] e : dirs) { + if (grid[i + e[0]].charAt(j + e[1]) == '0' || grid[i].charAt(j) == grid[i + e[0]].charAt(j + e[1])) { + p[find(i * n + j)] = find((i + e[0]) * n + j + e[1]); + } + } + } + } + } + Map mp = new HashMap<>(); + int res = 0; + for (int i = 0; i < m; ++i) { + for (int j = 0; j < n; ++j) { + int root = find(i * n + j); + if (root != find(m * n)) { + mp.put(root, mp.getOrDefault(root, 0) + 1); + res = Math.max(res, mp.get(root)); + } + } + } + return res; + } + + private int find(int x) { + if (p[x] != x) { + p[x] = find(p[x]); + } + return p[x]; + } +} \ No newline at end of file diff --git a/lcs/LCS 03. 主题空间/Solution.py b/lcs/LCS 03. 主题空间/Solution.py new file mode 100644 index 0000000000..698b809a70 --- /dev/null +++ b/lcs/LCS 03. 主题空间/Solution.py @@ -0,0 +1,28 @@ +class Solution: + def largestArea(self, grid: List[str]) -> int: + m, n = len(grid), len(grid[0]) + p = list(range(m * n + 1)) + + def find(x): + if p[x] != x: + p[x] = find(p[x]) + return p[x] + + for i in range(m): + for j in range(n): + if i == 0 or i == m - 1 or j == 0 or j == n - 1 or grid[i][j] == '0': + p[find(i * n + j)] = find(m * n) + else: + for x, y in [(-1, 0), (1, 0), (0, -1), (0, 1)]: + if grid[i + x][j + y] == '0' or grid[i][j] == grid[i + x][j + y]: + p[find(i * n + j)] = find((i + x) * n + j + y) + + mp = collections.defaultdict(int) + res = 0 + for i in range(m): + for j in range(n): + root = find(i * n + j) + if root != find(m * n): + mp[root] += 1 + res = max(res, mp[root]) + return res