Skip to main content

Find the Width of Columns of a Grid

Problem 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.

Examples​

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
  • (-10^9) <= grid[r][c] <= 10^9

Approach​

  • To find the maximum length of any number we can just convert it to a string and find it length.
  • In this way, we can easily find the maximum width of each column.

Complexity​

Time complexity: O(n∗n)O(n*n)

Space complexity: O(1)O(1)

Solution​

Code in Different Languages​

C++​

class Solution {
public:
vector<int> findColumnWidth(vector<vector<int>>& grid) {
int m = grid.size(), n = grid[0].size();
vector<int> ans(n);

for(int j=0; j<n; j++){
int l=0;
for(int i=0; i<m; i++){
l = max(l, int(to_string(grid[i][j]).size()));
}
ans[j] = l;
}
return ans;
}
};

JAVA​

class Solution {
public int[] findColumnWidth(int[][] grid) {
int m=grid.length,n=grid[0].length;
int ans[]=new int[n];
for(int i=0;i<n;i++)
{
int max=0;
for(int j=0;j<m;j++)
{
max=Math.max(max,String.valueOf(grid[j][i]).length());
}
ans[i]=max;
}
return ans;
}
}

PYTHON​

def findColumnWidth(self, A: List[List[int]]) -> List[int]:
return [max(len(str(a)) for a in r) for r in zip(*A)]

Complexity Analysis​

  • Time Complexity: O(n∗m)O(n*m)

  • Space Complexity: O(1)O(1)

References​

  • LeetCode Problem: Find the Width of Columns of a Grid