From 5ce3c9f25f5e8e76af21d2da5b0cb4679a8ead18 Mon Sep 17 00:00:00 2001 From: yanglbme Date: Tue, 29 Aug 2023 16:57:34 +0800 Subject: [PATCH] feat: add solutions to lc problem: No.2282 No.2282.Number of People That Can Be Seen in a Grid --- .../README.md | 4 + .../README.md | 205 +++++++++++++++++- .../README_EN.md | 185 +++++++++++++++- .../Solution.cpp | 40 ++++ .../Solution.go | 35 +++ .../Solution.java | 40 ++++ .../Solution.py | 24 ++ .../Solution.ts | 37 ++++ 8 files changed, 568 insertions(+), 2 deletions(-) create mode 100644 solution/2200-2299/2282.Number of People That Can Be Seen in a Grid/Solution.cpp create mode 100644 solution/2200-2299/2282.Number of People That Can Be Seen in a Grid/Solution.go create mode 100644 solution/2200-2299/2282.Number of People That Can Be Seen in a Grid/Solution.java create mode 100644 solution/2200-2299/2282.Number of People That Can Be Seen in a Grid/Solution.py create mode 100644 solution/2200-2299/2282.Number of People That Can Be Seen in a Grid/Solution.ts diff --git a/solution/1900-1999/1944.Number of Visible People in a Queue/README.md b/solution/1900-1999/1944.Number of Visible People in a Queue/README.md index 3331512555da4..7f3fd277f98db 100644 --- a/solution/1900-1999/1944.Number of Visible People in a Queue/README.md +++ b/solution/1900-1999/1944.Number of Visible People in a Queue/README.md @@ -66,6 +66,10 @@ 时间复杂度 $O(n)$，空间复杂度 $O(n)$。其中 $n$ 是数组 $heights$ 的长度。 +相似题目： + +- [2282. 在一个网格中可以看到的人数](/solution/2200-2299/2282.Number%20of%20People%20That%20Can%20Be%20Seen%20in%20a%20Grid/README.md) + ### **Python3** diff --git a/solution/2200-2299/2282.Number of People That Can Be Seen in a Grid/README.md b/solution/2200-2299/2282.Number of People That Can Be Seen in a Grid/README.md index 1c24c182e56e5..7fb983f55d108 100644 --- a/solution/2200-2299/2282.Number of People That Can Be Seen in a Grid/README.md +++ b/solution/2200-2299/2282.Number of People That Can Be Seen in a Grid/README.md @@ -59,6 +59,26 @@ +**方法一：单调栈** + +我们观察发现，对于第 $i$ 个人来说，他能看到的人一定是按从左到右（或者从上到下）高度严格单调递增的。 + +因此，对于每一行，我们可以用单调栈来求出每个人能看到的人数。 + +具体地，我们可以倒序遍历数组，用一个从栈顶到栈底单调递增的栈 $stk$ 记录已经遍历过的人的高度。 + +对于第 $i$ 个人，如果栈不为空并且栈顶元素小于 $heights[i]$，累加当前第 $i$ 个人能看到的人数，然后将栈顶元素出栈，直到栈为空或者栈顶元素大于等于 $heights[i]$。如果此时栈不为空，说明栈顶元素大于等于 $heights[i]$，那么第 $i$ 个人能看到的人数还要再加 $1$。接下来，如果栈不为空并且栈顶元素等于 $heights[i]$，那么栈顶元素出栈。最后，将 $heights[i]$ 入栈，继续遍历下一个人。 + +这样处理过后，我们就可以得到每一行每个人能看到的人数。 + +同理，我们可以对每一列进行处理，得到每一列每个人能看到的人数。最后，我们将每一行和每一列的答案相加，就可以得到最终的答案。 + +时间复杂度 $O(m \times n)$，空间复杂度 $O(\max(m, n))$。其中 $m$ 和 $n$ 分别是数组 $heights$ 的行数和列数。 + +相似题目： + +- [1944. 队列中可以看到的人数](/solution/1900-1999/1944.Number%20of%20Visible%20People%20in%20a%20Queue/README.md) + ### **Python3** @@ -66,7 +86,30 @@ ```python +class Solution: + def seePeople(self, heights: List[List[int]]) -> List[List[int]]: + def f(nums: List[int]) -> List[int]: + n = len(nums) + stk = [] + ans = [0] * n + for i in range(n - 1, -1, -1): + while stk and stk[-1] < nums[i]: + ans[i] += 1 + stk.pop() + if stk: + ans[i] += 1 + while stk and stk[-1] == nums[i]: + stk.pop() + stk.append(nums[i]) + return ans + ans = [f(row) for row in heights] + m, n = len(heights), len(heights[0]) + for j in range(n): + add = f([heights[i][j] for i in range(m)]) + for i in range(m): + ans[i][j] += add[i] + return ans ``` ### **Java** @@ -74,13 +117,173 @@ ```java +class Solution { + public int[][] seePeople(int[][] heights) { + int m = heights.length, n = heights[0].length; + int[][] ans = new int[m][0]; + for (int i = 0; i < m; ++i) { + ans[i] = f(heights[i]); + } + for (int j = 0; j < n; ++j) { + int[] nums = new int[m]; + for (int i = 0; i < m; ++i) { + nums[i] = heights[i][j]; + } + int[] add = f(nums); + for (int i = 0; i < m; ++i) { + ans[i][j] += add[i]; + } + } + return ans; + } + + private int[] f(int[] nums) { + int n = nums.length; + int[] ans = new int[n]; + Deque stk = new ArrayDeque<>(); + for (int i = n - 1; i >= 0; --i) { + while (!stk.isEmpty() && stk.peek() < nums[i]) { + stk.pop(); + ++ans[i]; + } + if (!stk.isEmpty()) { + ++ans[i]; + } + while (!stk.isEmpty() && stk.peek() == nums[i]) { + stk.pop(); + } + stk.push(nums[i]); + } + return ans; + } +} +``` + +### **C++** +```cpp +class Solution { +public: + vector> seePeople(vector>& heights) { + int m = heights.size(), n = heights[0].size(); + auto f = [](vector& nums) { + int n = nums.size(); + vector ans(n); + stack stk; + for (int i = n - 1; ~i; --i) { + while (stk.size() && stk.top() < nums[i]) { + ++ans[i]; + stk.pop(); + } + if (stk.size()) { + ++ans[i]; + } + while (stk.size() && stk.top() == nums[i]) { + stk.pop(); + } + stk.push(nums[i]); + } + return ans; + }; + vector> ans; + for (auto& row : heights) { + ans.push_back(f(row)); + } + for (int j = 0; j < n; ++j) { + vector col; + for (int i = 0; i < m; ++i) { + col.push_back(heights[i][j]); + } + vector add = f(col); + for (int i = 0; i < m; ++i) { + ans[i][j] += add[i]; + } + } + return ans; + } +}; +``` + +### **Go** + +```go +func seePeople(heights [][]int) (ans [][]int) { + f := func(nums []int) []int { + n := len(nums) + ans := make([]int, n) + stk := []int{} + for i := n - 1; i >= 0; i-- { + for len(stk) > 0 && stk[len(stk)-1] < nums[i] { + ans[i]++ + stk = stk[:len(stk)-1] + } + if len(stk) > 0 { + ans[i]++ + } + for len(stk) > 0 && stk[len(stk)-1] == nums[i] { + stk = stk[:len(stk)-1] + } + stk = append(stk, nums[i]) + } + return ans + } + for _, row := range heights { + ans = append(ans, f(row)) + } + n := len(heights[0]) + for j := 0; j < n; j++ { + col := make([]int, len(heights)) + for i := range heights { + col[i] = heights[i][j] + } + for i, v := range f(col) { + ans[i][j] += v + } + } + return +} ``` ### **TypeScript** ```ts - +function seePeople(heights: number[][]): number[][] { + const f = (nums: number[]): number[] => { + const n = nums.length; + const ans: number[] = new Array(n).fill(0); + const stk: number[] = []; + for (let i = n - 1; ~i; --i) { + while (stk.length && stk.at(-1) < nums[i]) { + stk.pop(); + ++ans[i]; + } + if (stk.length) { + ++ans[i]; + } + while (stk.length && stk.at(-1) === nums[i]) { + stk.pop(); + } + stk.push(nums[i]); + } + return ans; + }; + const ans: number[][] = []; + for (const row of heights) { + ans.push(f(row)); + } + const n = heights[0].length; + for (let j = 0; j < n; ++j) { + const col: number[] = []; + for (const row of heights) { + col.push(row[j]); + } + const add = f(col); + for (let i = 0; i < ans.length; ++i) { + ans[i][j] += add[i]; + } + } + return ans; +} ``` ### **...** diff --git a/solution/2200-2299/2282.Number of People That Can Be Seen in a Grid/README_EN.md b/solution/2200-2299/2282.Number of People That Can Be Seen in a Grid/README_EN.md index 1e9ecda583c1b..6d112f3354463 100644 --- a/solution/2200-2299/2282.Number of People That Can Be Seen in a Grid/README_EN.md +++ b/solution/2200-2299/2282.Number of People That Can Be Seen in a Grid/README_EN.md @@ -60,19 +60,202 @@ ### **Python3** ```python +class Solution: + def seePeople(self, heights: List[List[int]]) -> List[List[int]]: + def f(nums: List[int]) -> List[int]: + n = len(nums) + stk = [] + ans = [0] * n + for i in range(n - 1, -1, -1): + while stk and stk[-1] < nums[i]: + ans[i] += 1 + stk.pop() + if stk: + ans[i] += 1 + while stk and stk[-1] == nums[i]: + stk.pop() + stk.append(nums[i]) + return ans + ans = [f(row) for row in heights] + m, n = len(heights), len(heights[0]) + for j in range(n): + add = f([heights[i][j] for i in range(m)]) + for i in range(m): + ans[i][j] += add[i] + return ans ``` ### **Java** ```java +class Solution { + public int[][] seePeople(int[][] heights) { + int m = heights.length, n = heights[0].length; + int[][] ans = new int[m][0]; + for (int i = 0; i < m; ++i) { + ans[i] = f(heights[i]); + } + for (int j = 0; j < n; ++j) { + int[] nums = new int[m]; + for (int i = 0; i < m; ++i) { + nums[i] = heights[i][j]; + } + int[] add = f(nums); + for (int i = 0; i < m; ++i) { + ans[i][j] += add[i]; + } + } + return ans; + } + private int[] f(int[] nums) { + int n = nums.length; + int[] ans = new int[n]; + Deque stk = new ArrayDeque<>(); + for (int i = n - 1; i >= 0; --i) { + while (!stk.isEmpty() && stk.peek() < nums[i]) { + stk.pop(); + ++ans[i]; + } + if (!stk.isEmpty()) { + ++ans[i]; + } + while (!stk.isEmpty() && stk.peek() == nums[i]) { + stk.pop(); + } + stk.push(nums[i]); + } + return ans; + } +} +``` + +### **C++** + +```cpp +class Solution { +public: + vector> seePeople(vector>& heights) { + int m = heights.size(), n = heights[0].size(); + auto f = [](vector& nums) { + int n = nums.size(); + vector ans(n); + stack stk; + for (int i = n - 1; ~i; --i) { + while (stk.size() && stk.top() < nums[i]) { + ++ans[i]; + stk.pop(); + } + if (stk.size()) { + ++ans[i]; + } + while (stk.size() && stk.top() == nums[i]) { + stk.pop(); + } + stk.push(nums[i]); + } + return ans; + }; + vector> ans; + for (auto& row : heights) { + ans.push_back(f(row)); + } + for (int j = 0; j < n; ++j) { + vector col; + for (int i = 0; i < m; ++i) { + col.push_back(heights[i][j]); + } + vector add = f(col); + for (int i = 0; i < m; ++i) { + ans[i][j] += add[i]; + } + } + return ans; + } +}; +``` + +### **Go** + +```go +func seePeople(heights [][]int) (ans [][]int) { + f := func(nums []int) []int { + n := len(nums) + ans := make([]int, n) + stk := []int{} + for i := n - 1; i >= 0; i-- { + for len(stk) > 0 && stk[len(stk)-1] < nums[i] { + ans[i]++ + stk = stk[:len(stk)-1] + } + if len(stk) > 0 { + ans[i]++ + } + for len(stk) > 0 && stk[len(stk)-1] == nums[i] { + stk = stk[:len(stk)-1] + } + stk = append(stk, nums[i]) + } + return ans + } + for _, row := range heights { + ans = append(ans, f(row)) + } + n := len(heights[0]) + for j := 0; j < n; j++ { + col := make([]int, len(heights)) + for i := range heights { + col[i] = heights[i][j] + } + for i, v := range f(col) { + ans[i][j] += v + } + } + return +} ``` ### **TypeScript** ```ts - +function seePeople(heights: number[][]): number[][] { + const f = (nums: number[]): number[] => { + const n = nums.length; + const ans: number[] = new Array(n).fill(0); + const stk: number[] = []; + for (let i = n - 1; ~i; --i) { + while (stk.length && stk.at(-1) < nums[i]) { + stk.pop(); + ++ans[i]; + } + if (stk.length) { + ++ans[i]; + } + while (stk.length && stk.at(-1) === nums[i]) { + stk.pop(); + } + stk.push(nums[i]); + } + return ans; + }; + const ans: number[][] = []; + for (const row of heights) { + ans.push(f(row)); + } + const n = heights[0].length; + for (let j = 0; j < n; ++j) { + const col: number[] = []; + for (const row of heights) { + col.push(row[j]); + } + const add = f(col); + for (let i = 0; i < ans.length; ++i) { + ans[i][j] += add[i]; + } + } + return ans; +} ``` ### **...** diff --git a/solution/2200-2299/2282.Number of People That Can Be Seen in a Grid/Solution.cpp b/solution/2200-2299/2282.Number of People That Can Be Seen in a Grid/Solution.cpp new file mode 100644 index 0000000000000..625af4abf200c --- /dev/null +++ b/solution/2200-2299/2282.Number of People That Can Be Seen in a Grid/Solution.cpp @@ -0,0 +1,40 @@ +class Solution { +public: + vector> seePeople(vector>& heights) { + int m = heights.size(), n = heights[0].size(); + auto f = [](vector& nums) { + int n = nums.size(); + vector ans(n); + stack stk; + for (int i = n - 1; ~i; --i) { + while (stk.size() && stk.top() < nums[i]) { + ++ans[i]; + stk.pop(); + } + if (stk.size()) { + ++ans[i]; + } + while (stk.size() && stk.top() == nums[i]) { + stk.pop(); + } + stk.push(nums[i]); + } + return ans; + }; + vector> ans; + for (auto& row : heights) { + ans.push_back(f(row)); + } + for (int j = 0; j < n; ++j) { + vector col; + for (int i = 0; i < m; ++i) { + col.push_back(heights[i][j]); + } + vector add = f(col); + for (int i = 0; i < m; ++i) { + ans[i][j] += add[i]; + } + } + return ans; + } +}; \ No newline at end of file diff --git a/solution/2200-2299/2282.Number of People That Can Be Seen in a Grid/Solution.go b/solution/2200-2299/2282.Number of People That Can Be Seen in a Grid/Solution.go new file mode 100644 index 0000000000000..2e6d8bf66e8b0 --- /dev/null +++ b/solution/2200-2299/2282.Number of People That Can Be Seen in a Grid/Solution.go @@ -0,0 +1,35 @@ +func seePeople(heights [][]int) (ans [][]int) { + f := func(nums []int) []int { + n := len(nums) + ans := make([]int, n) + stk := []int{} + for i := n - 1; i >= 0; i-- { + for len(stk) > 0 && stk[len(stk)-1] < nums[i] { + ans[i]++ + stk = stk[:len(stk)-1] + } + if len(stk) > 0 { + ans[i]++ + } + for len(stk) > 0 && stk[len(stk)-1] == nums[i] { + stk = stk[:len(stk)-1] + } + stk = append(stk, nums[i]) + } + return ans + } + for _, row := range heights { + ans = append(ans, f(row)) + } + n := len(heights[0]) + for j := 0; j < n; j++ { + col := make([]int, len(heights)) + for i := range heights { + col[i] = heights[i][j] + } + for i, v := range f(col) { + ans[i][j] += v + } + } + return +} \ No newline at end of file diff --git a/solution/2200-2299/2282.Number of People That Can Be Seen in a Grid/Solution.java b/solution/2200-2299/2282.Number of People That Can Be Seen in a Grid/Solution.java new file mode 100644 index 0000000000000..b2f104d13fe21 --- /dev/null +++ b/solution/2200-2299/2282.Number of People That Can Be Seen in a Grid/Solution.java @@ -0,0 +1,40 @@ +class Solution { + public int[][] seePeople(int[][] heights) { + int m = heights.length, n = heights[0].length; + int[][] ans = new int[m][0]; + for (int i = 0; i < m; ++i) { + ans[i] = f(heights[i]); + } + for (int j = 0; j < n; ++j) { + int[] nums = new int[m]; + for (int i = 0; i < m; ++i) { + nums[i] = heights[i][j]; + } + int[] add = f(nums); + for (int i = 0; i < m; ++i) { + ans[i][j] += add[i]; + } + } + return ans; + } + + private int[] f(int[] nums) { + int n = nums.length; + int[] ans = new int[n]; + Deque stk = new ArrayDeque<>(); + for (int i = n - 1; i >= 0; --i) { + while (!stk.isEmpty() && stk.peek() < nums[i]) { + stk.pop(); + ++ans[i]; + } + if (!stk.isEmpty()) { + ++ans[i]; + } + while (!stk.isEmpty() && stk.peek() == nums[i]) { + stk.pop(); + } + stk.push(nums[i]); + } + return ans; + } +} \ No newline at end of file diff --git a/solution/2200-2299/2282.Number of People That Can Be Seen in a Grid/Solution.py b/solution/2200-2299/2282.Number of People That Can Be Seen in a Grid/Solution.py new file mode 100644 index 0000000000000..aa4dce96638ca --- /dev/null +++ b/solution/2200-2299/2282.Number of People That Can Be Seen in a Grid/Solution.py @@ -0,0 +1,24 @@ +class Solution: + def seePeople(self, heights: List[List[int]]) -> List[List[int]]: + def f(nums: List[int]) -> List[int]: + n = len(nums) + stk = [] + ans = [0] * n + for i in range(n - 1, -1, -1): + while stk and stk[-1] < nums[i]: + ans[i] += 1 + stk.pop() + if stk: + ans[i] += 1 + while stk and stk[-1] == nums[i]: + stk.pop() + stk.append(nums[i]) + return ans + + ans = [f(row) for row in heights] + m, n = len(heights), len(heights[0]) + for j in range(n): + add = f([heights[i][j] for i in range(m)]) + for i in range(m): + ans[i][j] += add[i] + return ans diff --git a/solution/2200-2299/2282.Number of People That Can Be Seen in a Grid/Solution.ts b/solution/2200-2299/2282.Number of People That Can Be Seen in a Grid/Solution.ts new file mode 100644 index 0000000000000..75c02ad2a2be9 --- /dev/null +++ b/solution/2200-2299/2282.Number of People That Can Be Seen in a Grid/Solution.ts @@ -0,0 +1,37 @@ +function seePeople(heights: number[][]): number[][] { + const f = (nums: number[]): number[] => { + const n = nums.length; + const ans: number[] = new Array(n).fill(0); + const stk: number[] = []; + for (let i = n - 1; ~i; --i) { + while (stk.length && stk.at(-1) < nums[i]) { + stk.pop(); + ++ans[i]; + } + if (stk.length) { + ++ans[i]; + } + while (stk.length && stk.at(-1) === nums[i]) { + stk.pop(); + } + stk.push(nums[i]); + } + return ans; + }; + const ans: number[][] = []; + for (const row of heights) { + ans.push(f(row)); + } + const n = heights[0].length; + for (let j = 0; j < n; ++j) { + const col: number[] = []; + for (const row of heights) { + col.push(row[j]); + } + const add = f(col); + for (let i = 0; i < ans.length; ++i) { + ans[i][j] += add[i]; + } + } + return ans; +}