Nested Array: How to use && operator properly to skip some loops?

user_1088949 0
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I'm trying to get an "hourglass" array out from a nested array.

Say that this array is

1 1 1 0 0 0
0 1 0 0 0 0
1 1 1 0 0 0

I have to get this "hourglass" array out and add it all up:

1 1 1
  1
1 1 1

Therefore, here's my attempt:

for (let i = 0; i < 3; i++) {
    for (let j = 0; j < 3; j++) {
        if ((i === 1 && j === 0) && (i === 1 && j === 2)) {
            continue;
        } else {
            newArr.push(arr[i][j]);
        }
    }
}

I noticed that if I use this condition: i === 1 && j === 0, it was able to skip over the position at i = 1 and j = 0 but when I added j = 2, I couldn't get it to skip over the first and third positions. Therefore, I was trying out various options to get it to work but I couldn't get it to work. Such, I was wondering if I'm doing the && operator correctly?

arrays javascript
2 Answers

You could add spaces for the zeros (0) and for the ones (1) or maybe any other number just accumulate them;

const arr = [
  [1, 1, 1, 0, 0, 0],
  [0, 1, 0, 0, 0, 0],
  [1, 1, 1, 0, 0, 0],
]
let printRow = '';
for (let i = 0; i < arr.length; i++) {
  for (let j = 0; j < arr[i].length; j++) {
    if (arr[i][j] === 0) {
      printRow += ' ';
    } else {
      printRow += arr[i][j];
    }
  }
  console.log(printRow);
  printRow = '';
}

user_29519330

Solution

To find every hourglass in this grid 3 rows 6 columns grid with only one loop
Notice: When the Grid becomes larger you have to use an inner for loop

    const arr = [
        [1, 1, 1, 0, 0, 0],
        [0, 1, 0, 0, 0, 0],
        [1, 1, 1, 0, 0, 0],
      ]  
       // format is [row][column]  
       let result;
       let topp;
       let mid;
       let bottom;
       for (let i = 0; i < 4; i++) {
      
               // this ist the filter defining what we are looking for
           if (arr[0][i] === 1 && arr[0][i+1] === 1 && arr[0][i + 2] === 1 &&
               arr[1][i] === 0 && arr[1][i+1] === 1 && arr[1][i + 2] === 0 &&
               arr[2][i] === 1 && arr[2][i+1] === 1 && arr[2][i + 2] === 1) {
               
              // here we build the string        
               topp = arr[0][i] +  " " + arr[0][i+1] + " " + arr[0][i+2];
               mid = arr[1][i] + " " + arr[1][i+1] + " " + arr[1][i+2];
               bottom = arr[2][i] + " " + arr[2][i+1] + " " + arr[2][i + 2];
       
               result = topp + "\n" + mid + "\n" + bottom;
               
           }
       }
       console.log(result)

user_147470390
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