[2428] Hour Glass Sum

LeetcodeProblems/Algorithms/Maximise_Hour_Glass_Sum.js

@@ -0,0 +1,48 @@
+/*
+2428. Maximum Sum of an Hourglass
+
+You are given an m x n integer matrix grid.
+We define an hourglass as a part of the matrix with the following form:
+For Input : [[6,2,1],[4,2,1],[9,2,8]]
+The Hourglass sum would be => 6 + 2 + 1 + 2( 2nd row , 2nd column) + 9 + 2 + 8
+
+Return the maximum sum of the elements of an hourglass.
+
+Note that an hourglass cannot be rotated and must be entirely contained within the matrix.
+
+Constraints:
+
+m == grid.length
+n == grid[i].length
+3 <= m, n <= 150
+0 <= grid[i][j] <= 106
+
+Input: grid = [[6,2,1,3],[4,2,1,5],[9,2,8,7],[4,1,2,9]]
+Output: 30
+Explanation: The cells shown above represent the hourglass with the maximum sum: 6 + 2 + 1 + 2 + 9 + 2 + 8 = 30.
+
+
+Input: grid = [[1,2,3],[4,5,6],[7,8,9]]
+Output: 35
+Explanation: There is only one hourglass in the matrix, with the sum: 1 + 2 + 3 + 5 + 7 + 8 + 9 = 35.
+*/
+
+/**
+ * @param {number[][]} grid
+ * @return {number}
+ */
+ var maxSum = function(grid) {
+  const m = grid.length;
+  const n = grid[0].length;
+  if(m<3 || n < 3) {
+      return 0;
+  }
+  let max = 0;
+  for(let i = 0; i<m-2; i++)
+      for(let j = 0; j<n-2;j++)
+      {
+          let cur = grid[i][j] + grid[i][j+1] + grid[i][j+2] + grid[i+1][j+1] + grid[i+2][j] + grid[i+2][j+1] + grid[i+2][j+2];
+          max = Math.max(cur, max);
+      }
+  return max;  
+};

LeetcodeProblemsTests/Algorithms/Maximise_Hour_Glass_Sum.js

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+const assert = require('assert');
+const maxSum = require('../../LeetcodeProblems/Algorithms/Maximise_Hour_Glass_Sum').maxSum;
+
+function test() {
+  assert.equal(maxSum([[6,2,1,3],[4,2,1,5],[9,2,8,7],[4,1,2,9]]));
+  assert.equal(maxSum([[1,2,3],[4,5,6],[7,8,9]]));
+}
+
+module.exports.test = test

README.md

@@ -61,6 +61,7 @@ To run a specific problem in your console run  `node <problem_file_path>` (e.g.
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+| [Maximum Sum of an Hourglass](/LeetcodeProblems/Algorithms/Maximise_Hour_Glass_Sum.js)                          | Medium | https://leetcode.com/problems/maximum-sum-of-an-hourglass/ |
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