Merge pull request #1039 from 0xff-dev/2257

Add solution and test-cases for problem 2257

Author: 6boris

leetcode/2201-2300/2257.Count-Unguarded-Cells-in-the-Grid/1.png

@@ -1,28 +1,33 @@
 # [2257.Count Unguarded Cells in the Grid][title]
 
-> [!WARNING|style:flat]
-> This question is temporarily unanswered if you have good ideas. Welcome to [Create Pull Request PR](https://github.com/kylesliu/awesome-golang-algorithm)
-
 ## Description
+You are given two integers m and n representing a **0-indexed** `m x n` grid. You are also given two 2D integer arrays `guards` and `walls` where `guards[i] = [rowi, coli]` and `walls[j] = [rowj, colj]` represent the positions of the `ith` guard and `jth` wall respectively.
+
+A guard can see **every** cell in the four cardinal directions (north, east, south, or west) starting from their position unless **obstructed** by a wall or another guard. A cell is **guarded** if there is **at least** one guard that can see it.
+
+Return the number of unoccupied cells that are **not guarded**.
 
-**Example 1:**
+**Example 1:**  
+
+![1](./1.png)
 
 ```
-Input: a = "11", b = "1"
-Output: "100"
+Input: m = 4, n = 6, guards = [[0,0],[1,1],[2,3]], walls = [[0,1],[2,2],[1,4]]
+Output: 7
+Explanation: The guarded and unguarded cells are shown in red and green respectively in the above diagram.
+There are a total of 7 unguarded cells, so we return 7.
 ```
 
-## 题意
-> ...
+**Example 2:**  
 
-## 题解
+![2](./2.png)
 
-### 思路1
-> ...
-Count Unguarded Cells in the Grid
-```go
 ```
-
+Input: m = 3, n = 3, guards = [[1,1]], walls = [[0,1],[1,0],[2,1],[1,2]]
+Output: 4
+Explanation: The unguarded cells are shown in green in the above diagram.
+There are a total of 4 unguarded cells, so we return 4.
+```
 
 ## 结语
 

leetcode/2201-2300/2257.Count-Unguarded-Cells-in-the-Grid/2.png

@@ -1,5 +1,78 @@
 package Solution
 
-func Solution(x bool) bool {
-	return x
+func Solution(m int, n int, guards [][]int, walls [][]int) int {
+	count := m * n
+	count -= len(guards)
+	count -= len(walls)
+	wm := make(map[int]map[int]struct{})
+	for _, w := range walls {
+		if _, ok := wm[w[0]]; !ok {
+			wm[w[0]] = make(map[int]struct{})
+		}
+		wm[w[0]][w[1]] = struct{}{}
+	}
+	gm := make(map[int]map[int]struct{})
+	for _, g := range guards {
+		if _, ok := gm[g[0]]; !ok {
+			gm[g[0]] = make(map[int]struct{})
+		}
+		gm[g[0]][g[1]] = struct{}{}
+	}
+
+	used := make(map[[2]int]struct{})
+	for _, g := range guards {
+		x, y := g[0], g[1]
+		for i := x - 1; i >= 0; i-- {
+			if v, ok := gm[i]; ok {
+				if _, ok := v[y]; ok {
+					break
+				}
+			}
+			if v, ok := wm[i]; ok {
+				if _, ok := v[y]; ok {
+					break
+				}
+			}
+			used[[2]int{i, y}] = struct{}{}
+		}
+
+		for i := x + 1; i < m; i++ {
+			if v, ok := gm[i]; ok {
+				if _, ok := v[y]; ok {
+					break
+				}
+			}
+			if v, ok := wm[i]; ok {
+				if _, ok := v[y]; ok {
+					break
+				}
+			}
+			used[[2]int{i, y}] = struct{}{}
+		}
+
+		rows := gm[x]
+		for i := y + 1; i < n; i++ {
+			if _, ok := rows[i]; ok {
+				break
+			}
+			if v, ok := wm[x]; ok {
+				if _, ok := v[i]; ok {
+					break
+				}
+			}
+			used[[2]int{x, i}] = struct{}{}
+		}
+		for i := y - 1; i >= 0; i-- {
+			if _, ok := rows[i]; ok {
+				break
+			}
+			if v, ok := wm[x]; ok {
+				if _, ok := v[i]; ok {
+					break
+				}
+			}
+			used[[2]int{x, i}] = struct{}{}
+		}
+	}
+	return count - len(used)
 }

leetcode/2201-2300/2257.Count-Unguarded-Cells-in-the-Grid/README.md

@@ -9,31 +9,31 @@ import (
 func TestSolution(t *testing.T) {
 	//	测试用例
 	cases := []struct {
-		name   string
-		inputs bool
-		expect bool
+		name          string
+		m, n          int
+		guards, walls [][]int
+		expect        int
 	}{
-		{"TestCase", true, true},
-		{"TestCase", true, true},
-		{"TestCase", false, false},
+		{"TestCase1", 4, 6, [][]int{{0, 0}, {1, 1}, {2, 3}}, [][]int{{0, 1}, {2, 2}, {1, 4}}, 7},
+		{"TestCase2", 3, 3, [][]int{{1, 1}}, [][]int{{0, 1}, {1, 0}, {2, 1}, {1, 2}}, 4},
 	}
 
 	//	开始测试
 	for i, c := range cases {
 		t.Run(c.name+" "+strconv.Itoa(i), func(t *testing.T) {
-			got := Solution(c.inputs)
+			got := Solution(c.m, c.n, c.guards, c.walls)
 			if !reflect.DeepEqual(got, c.expect) {
-				t.Fatalf("expected: %v, but got: %v, with inputs: %v",
-					c.expect, got, c.inputs)
+				t.Fatalf("expected: %v, but got: %v, with inputs: %v %v %v %v",
+					c.expect, got, c.m, c.n, c.guards, c.walls)
 			}
 		})
 	}
 }
 
-//	压力测试
+// 压力测试
 func BenchmarkSolution(b *testing.B) {
 }
 
-//	使用案列
+// 使用案列
 func ExampleSolution() {
 }