HyeGyeong
HyeGyeong 프로그래머를 꿈꾸며 JavaScript 공부 중

[Algorithm] HackerRank day11

[Algorithm] HackerRank day11

Today, we’re building on our knowledge of Arrays by adding another dimension. Check out the Tutorial tab for learning materials and an instructional video!

Context

Given a 6 × 6 2D Array, A:

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5
6

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

We define an hourglass in A to be a subset of values with indices falling in this pattern in A’s graphical representation:

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3

a b c
  d
e f g

There are 16 hourglasses in A, and an hourglass sum is the sum of an hourglass’ values.

Task

There are 6 lines of input, where each line contains 6 space-separated integers describing 2D Array A; every value in A will be in the inclusive range of -9 to 9.

Constraints

  • -9 ≤ A[i][j] ≤ 9
  • 0 ≤ i,j ≤ 5

Output Format

Print the largest (maximum) hourglass sum found in A.

Sample Input

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6

1 1 1 0 0 0
0 1 0 0 0 0
1 1 1 0 0 0
0 0 2 4 4 0
0 0 0 2 0 0
0 0 1 2 4 0

Sample Output

1

19

Explanation

A contains the following hourglasses:

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15

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

0 1 0   1 0 0   0 0 0   0 0 0
  1       1       0       0
0 0 2   0 2 4   2 4 4   4 4 0

1 1 1   1 1 0   1 0 0   0 0 0
  0       2       4       4
0 0 0   0 0 2   0 2 0   2 0 0

0 0 2   0 2 4   2 4 4   4 4 0
  0       0       2       0
0 0 1   0 1 2   1 2 4   2 4 0

The hourglass with the maximum sum (19) is:

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3

2 4 4
  2
1 2 4

Solve

  • 모래시계 형태의 수가 6 × 6 arr에 있을 때 가장 큰 합을 return한다.
  • 모래시계 형태로 직접 넣어서 합을 구했는데 더 좋은 방법이 있는지 고민할 것.
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function main() {
  let arr = Array(6);
  let maxTotal;

  // 문제에 입력된 수를 6 × 6 Array 형태로 만들어주는 부분
  for (let i = 0; i < 6; i++) {
    arr[i] = readLine()
      .split(' ')
      .map(arrTemp => parseInt(arrTemp, 10));
  }

  for (let i = 0; i < arr.length - 2; i++) {
    for (let j = 0; j < arr.length - 2; j++) {
      // hourglasses 형태를 갖춘 위치의 수를 모두 합함.
      let total =
        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];

      if (!maxTotal && maxTotal !== 0) {
        maxTotal = total;
      }
      if (total > maxTotal) {
        maxTotal = total;
      }
    }
  }
  console.log(maxTotal);
  return maxTotal;
}

[출처: https://www.hackerrank.com]