2D Array - DS Discussions | Data Structures

Sort 2175 Discussions, By:

thegeeksam 5 years ago+ 0 comments

if you want to pass test Case 3 and 5 dont initialize max value to 0.

RishC 4 years ago+ 0 comments

Python3 answer

sum = []


for i in range(len(arr)-2):
    for j in range(len(arr)-2):
        sum.append(arr[i][j]+arr[i][j+1]+arr[i][j+2]+arr[i+1][j+1]+arr[i+2][j]+arr[i+2][j+1]+arr[i+2][j+2])
        
print(max(sum))

milad 4 years ago+ 0 comments

How the heck is this problem ranked as easy? Am I missing something or do people jus tlook at the solutions after 1 glance at the problem?

tony_cottam 5 years ago+ 0 comments

I think where most people are having problems (and where I was having problems) is that the array is being read in and then processed on opposite coordinates ( e.g. read in as (x, y) but then process as (y, x) ).

I decided this was the problem for me after I read in the array as a 1D array and then was able to solve no problem.

jhall1468 4 years ago+ 0 comments

A Javascript solution using O(n*m) time complexity and O(1) space complexity.

function hourGlass(arr) {
    // we could set this to 3 given the problems constraings, but this allows changes
    maxX = 3; // + (arr[0].length % 3)
    maxY = 3; // + (arr.length % 3)
    total = -Infinity;  // has to be -64, but
   
    // begin at y == 0
    for (let y = 0; y <= maxY; y++) {
        for (let x = 0; x <= maxX; x++) {
            // sum the top of hourglass
            let sum = arr[y][x] + arr[y][x+1] + arr[y][x+2];
            
            // get the middle of hourglass
            sum += arr[y+1][x+1];
            
            // sum the bottom of hourglass
            sum += arr[y+2][x] + arr[y+2][x+1] + arr[y+2][x+2]
            
            // don't store result to keep space complexity down
            if (total < sum)
                 total = sum;
        }
    }
    
    return total;
}

Load more conversations