Merge pull request #1310 from 0xff-dev/1139

Add solution and test-cases for problem 1139

Author: 6boris

leetcode/1101-1200/1139.Largest-1-Bordered-Square/README.md

@@ -1,28 +1,21 @@
 # [1139.Largest 1-Bordered Square][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
+Given a 2D `grid` of `0`s and `1`s, return the number of elements in the largest **square** subgrid that has all `1`s on its **border**, or 0 if such a subgrid doesn't exist in the `grid`.
 
 **Example 1:**
 
 ```
-Input: a = "11", b = "1"
-Output: "100"
+Input: grid = [[1,1,1],[1,0,1],[1,1,1]]
+Output: 9
 ```
 
-## 题意
-> ...
-
-## 题解
+**Example 2:**
 
-### 思路1
-> ...
-Largest 1-Bordered Square
-```go
 ```
-
+Input: grid = [[1,1,0,0]]
+Output: 1
+```
 
 ## 结语
 

leetcode/1101-1200/1139.Largest-1-Bordered-Square/Solution.go

@@ -1,5 +1,59 @@
 package Solution
 
-func Solution(x bool) bool {
-	return x
+type cell struct {
+	left, up int
+}
+
+func Solution(grid [][]int) int {
+	ans := 0
+	rows, cols := len(grid), len(grid[0])
+	count := make([][]cell, rows)
+	for i := range rows {
+		count[i] = make([]cell, cols)
+	}
+	for i := 0; i < rows; i++ {
+		pre := 0
+		for j := 0; j < cols; j++ {
+			if grid[i][j] == 1 {
+				pre++
+			} else {
+				pre = 0
+			}
+			count[i][j].left = pre
+		}
+	}
+	for j := 0; j < cols; j++ {
+		pre := 0
+		for i := 0; i < rows; i++ {
+			if grid[i][j] == 1 {
+				pre++
+			} else {
+				pre = 0
+			}
+			count[i][j].up = pre
+		}
+	}
+	for i := 0; i < rows; i++ {
+		for j := 0; j < cols; j++ {
+			if grid[i][j] == 0 {
+				continue
+			}
+			ans = max(ans, 1)
+			for l := 2; i+l-1 < rows && j+l-1 < cols; l++ {
+				x, y := i+l-1, j+l-1
+				if grid[x][y] == 0 {
+					continue
+				}
+
+				left := count[x][j].up - count[i][j].up + 1
+				bottom := count[x][y].left - count[x][j].left + 1
+				right := count[x][y].up - count[i][y].up + 1
+				top := count[i][y].left - count[i][j].left + 1
+				if left == l && bottom == l && right == l && top == l {
+					ans = max(ans, l)
+				}
+			}
+		}
+	}
+	return ans * ans
 }

leetcode/1101-1200/1139.Largest-1-Bordered-Square/Solution_test.go

@@ -10,12 +10,11 @@ func TestSolution(t *testing.T) {
 	//	测试用例
 	cases := []struct {
 		name   string
-		inputs bool
-		expect bool
+		inputs [][]int
+		expect int
 	}{
-		{"TestCase", true, true},
-		{"TestCase", true, true},
-		{"TestCase", false, false},
+		{"TestCase1", [][]int{{1, 1, 1}, {1, 0, 1}, {1, 1, 1}}, 9},
+		{"TestCase2", [][]int{{1, 1}, {0, 0}}, 1},
 	}
 
 	//	开始测试
@@ -30,10 +29,10 @@ func TestSolution(t *testing.T) {
 	}
 }
 
-//	压力测试
+// 压力测试
 func BenchmarkSolution(b *testing.B) {
 }
 
-//	使用案列
+// 使用案列
 func ExampleSolution() {
 }