complete hourglassSum

src/hourglassSum.js

@@ -0,0 +1,93 @@
+/*
+Given a 6x6 2D Array:
+
+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 arr's graphical representation:
+
+a b c
+  d
+e f g
+
+There are 16 hourglasses in arr, and an hourglass sum is the sum of an hourglass' values. Calculate the hourglass sum for every hourglass in , then print the maximum hourglass sum.
+
+For example, given the 2D array:
+
+-9 - 9 - 9  1 1 1
+0 - 9  0  4 3 2
+- 9 - 9 - 9  1 2 3
+0  0  8  6 6 0
+0  0  0 - 2 0 0
+0  0  1  2 4 0
+We calculate the following 16 hourglass values:
+
+-63, -34, -9, 12,
+-10, 0, 28, 23,
+-27, -11, -2, 10,
+9, 17, 25, 18
+
+Our highest hourglass value is 28 from the hourglass:
+
+0 4 3
+  1
+8 6 6
+
+Function Description:
+    Complete the function hourglassSum in the editor below. It should return an integer, the maximum hourglass sum in the array.
+*/
+
+function isNotAnEdge(x, y, arr) {
+  if (y > 0 && y <= arr.length - 2) {
+    if (x > 0 && x <= arr[y].length - 2) {
+      return true;
+    }
+  }
+  return false;
+}
+
+function calcHourglassSumm (x,y,arr) {
+    let sum = 0;
+    sum += arr[y+1][x-1]; // top left
+    sum += arr[y+1][x]; // top middle
+    sum += arr[y+1][x+1]; // top right
+    sum += arr[y][x]; // center
+    sum += arr[y-1][x-1]; // bottom left
+    sum += arr[y-1][x]; // bottom middle
+    sum += arr[y-1][x+1]; // bottom right
+    return sum;
+
+}
+
+function hourglassSum(arr) {
+    let maxHourglassSum = -Infinity;
+
+    for (let y = 0; y < arr.length; y++) {
+        for (let x = 0; x < arr[y].length; x++) {
+            if (isNotAnEdge(x, y, arr)) {
+                const hourglassResult = calcHourglassSumm(x,y,arr);
+                if (hourglassResult > maxHourglassSum) {
+                    maxHourglassSum = hourglassResult;
+                }
+            }
+        }
+    }
+    return maxHourglassSum;
+}
+
+// 28
+const test1 = [
+  [-9, -9, -9, 1, 1, 1],
+  [0, -9, 0, 4, 3, 2],
+  [-9, -9, -9, 1, 2, 3],
+  [0, 0, 8, 6, 6, 0],
+  [0, 0, 0, -2, 0, 0],
+  [0, 0, 1, 2, 4, 0]
+];
+
+console.log('hourglassSum(test1)', hourglassSum(test1));
+