LeetCode 2639. Find the Width of Columns of a Grid Solution in Java, C++, Python & More | Explanation + Code

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.

 

Constraints:

• m == grid.length
• n == grid[i].length
• 1 <= m, n <= 100
• -109 <= grid[r][c] <= 109

Solutions

Solution 1: Simulation

We denote the number of columns in the matrix as n, and create an array ans of length n, where ans[i] represents the width of the i-th column. Initially, ans[i] = 0.

We traverse each row in the matrix. For each element in each row, we calculate its string length w, and update the value of ans[j] to be max(ans[j], w).

After traversing all rows, each element in the array ans is the width of the corresponding column.

The time complexity is O(m × n), and the space complexity is O(log M). Where m and n are the number of rows and columns in the matrix respectively, and M is the absolute value of the maximum element in the matrix.

PythonJavaC++GoTypeScriptRust

class Solution: def findColumnWidth(self, grid: List[List[int]]) -> List[int]: return [max(len(str(x)) for x in col) for col in zip(*grid)](code-box)

class Solution { public int[] findColumnWidth(int[][] grid) { int n = grid[0].length; int[] ans = new int[n]; for (var row : grid) { for (int j = 0; j < n; ++j) { int w = String.valueOf(row[j]).length(); ans[j] = Math.max(ans[j], w); } } return ans; } }(code-box)

class Solution { public: vector<int> findColumnWidth(vector<vector<int>>& grid) { int n = grid[0].size(); vector<int> ans(n); for (auto& row : grid) { for (int j = 0; j < n; ++j) { int w = to_string(row[j]).size(); ans[j] = max(ans[j], w); } } return ans; } };(code-box)

func findColumnWidth(grid [][]int) []int { ans := make([]int, len(grid[0])) for _, row := range grid { for j, x := range row { w := len(strconv.Itoa(x)) ans[j] = max(ans[j], w) } } return ans }(code-box)

function findColumnWidth(grid: number[][]): number[] { const n = grid[0].length; const ans: number[] = new Array(n).fill(0); for (const row of grid) { for (let j = 0; j < n; ++j) { const w: number = String(row[j]).length; ans[j] = Math.max(ans[j], w); } } return ans; }(code-box)

impl Solution { pub fn find_column_width(grid: Vec<Vec<i32>>) -> Vec<i32> { let mut ans = vec![0; grid[0].len()]; for row in grid.iter() { for (j, num) in row.iter().enumerate() { let width = num.to_string().len() as i32; ans[j] = std::cmp::max(ans[j], width); } } ans } }(code-box)