Add solution and test-cases for problem 2639

Author: 0xff-dev

leetcode/2601-2700/2639.Find-the-Width-of-Columns-of-a-Grid/README.md

@@ -0,0 +1,36 @@
+# [2639.Find the Width of Columns of a Grid][title]
+
+## Description
+You are given a **0-indexed** `m x n` integer matrix `grid`. The width of a column is the maximum **length** of its integers.
+
+- For example, if `grid = [[-10], [3], [12]]`, the width of the only column is `3` since `-10` is of length `3`.
+
+Return an integer array `ans` of size n where `ans[i]` is the width of the `ith` column.
+
+The **length** of an integer `x` with `len` digits is equal to `len` if `x` is non-negative, and `len + 1` otherwise.
+
+**Example 1:**
+
+```
+Input: grid = [[1],[22],[333]]
+Output: [3]
+Explanation: In the 0th column, 333 is of length 3.
+```
+
+**Example 2:**
+
+```
+Input: grid = [[-15,1,3],[15,7,12],[5,6,-2]]
+Output: [3,1,2]
+Explanation: 
+In the 0th column, only -15 is of length 3.
+In the 1st column, all integers are of length 1. 
+In the 2nd column, both 12 and -2 are of length 2.
+```
+
+## 结语
+
+如果你同我一样热爱数据结构、算法、LeetCode，可以关注我 GitHub 上的 LeetCode 题解：[awesome-golang-algorithm][me]
+
+[title]: https://leetcode.com/problems/find-the-width-of-columns-of-a-grid
+[me]: https://github.com/kylesliu/awesome-golang-algorithm

leetcode/2601-2700/2639.Find-the-Width-of-Columns-of-a-Grid/Solution.go

@@ -1,5 +1,28 @@
 package Solution
 
-func Solution(x bool) bool {
-	return x
+func nBits(n int) int {
+	if n == 0 {
+		return 1
+	}
+	bits := 0
+	if n < 0 {
+		bits++
+		n = -n
+	}
+	for n > 0 {
+		n /= 10
+		bits++
+	}
+	return bits
+}
+
+func Solution(grid [][]int) []int {
+	rows, cols := len(grid), len(grid[0])
+	ret := make([]int, cols)
+	for r := 0; r < rows; r++ {
+		for c := 0; c < cols; c++ {
+			ret[c] = max(ret[c], nBits(grid[r][c]))
+		}
+	}
+	return ret
 }

leetcode/2601-2700/2639.Find-the-Width-of-Columns-of-a-Grid/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}, {22}, {333}}, []int{3}},
+		{"TestCase2", [][]int{{-15, 1, 3}, {15, 7, 12}, {5, 6, -2}}, []int{3, 1, 2}},
 	}
 
 	//	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() {
 }