Add solution #764

Author: JoshCrozier

0764-largest-plus-sign.js

@@ -0,0 +1,58 @@
+/**
+ * 764. Largest Plus Sign
+ * https://leetcode.com/problems/largest-plus-sign/
+ * Difficulty: Medium
+ *
+ * You are given an integer n. You have an n x n binary grid grid with all values initially
+ * 1's except for some indices given in the array mines. The ith element of the array mines
+ * is defined as mines[i] = [xi, yi] where grid[xi][yi] == 0.
+ *
+ * Return the order of the largest axis-aligned plus sign of 1's contained in grid. If
+ * there is none, return 0.
+ *
+ * An axis-aligned plus sign of 1's of order k has some center grid[r][c] == 1 along with four
+ * arms of length k - 1 going up, down, left, and right, and made of 1's. Note that there could
+ * be 0's or 1's beyond the arms of the plus sign, only the relevant area of the plus sign is
+ * checked for 1's.
+ */
+
+/**
+ * @param {number} n
+ * @param {number[][]} mines
+ * @return {number}
+ */
+function orderOfLargestPlusSign(n, mines) {
+  const grid = Array(n).fill().map(() => Array(n).fill(1));
+  mines.forEach(([x, y]) => grid[x][y] = 0);
+
+  const left = Array(n).fill().map(() => Array(n).fill(0));
+  const right = Array(n).fill().map(() => Array(n).fill(0));
+  const up = Array(n).fill().map(() => Array(n).fill(0));
+  const down = Array(n).fill().map(() => Array(n).fill(0));
+
+  for (let i = 0; i < n; i++) {
+    for (let j = 0; j < n; j++) {
+      left[i][j] = grid[i][j] ? (j > 0 ? left[i][j-1] + 1 : 1) : 0;
+      up[i][j] = grid[i][j] ? (i > 0 ? up[i-1][j] + 1 : 1) : 0;
+    }
+  }
+
+  for (let i = n - 1; i >= 0; i--) {
+    for (let j = n - 1; j >= 0; j--) {
+      right[i][j] = grid[i][j] ? (j < n-1 ? right[i][j+1] + 1 : 1) : 0;
+      down[i][j] = grid[i][j] ? (i < n-1 ? down[i+1][j] + 1 : 1) : 0;
+    }
+  }
+
+  let maxOrder = 0;
+  for (let i = 0; i < n; i++) {
+    for (let j = 0; j < n; j++) {
+      maxOrder = Math.max(
+        maxOrder,
+        Math.min(left[i][j], right[i][j], up[i][j], down[i][j])
+      );
+    }
+  }
+
+  return maxOrder;
+}

README.md

@@ -578,6 +578,7 @@
 761|[Special Binary String](./0761-special-binary-string.js)|Hard|
 762|[Prime Number of Set Bits in Binary Representation](./0762-prime-number-of-set-bits-in-binary-representation.js)|Easy|
 763|[Partition Labels](./0763-partition-labels.js)|Medium|
+764|[Largest Plus Sign](./0764-largest-plus-sign.js)|Medium|
 783|[Minimum Distance Between BST Nodes](./0783-minimum-distance-between-bst-nodes.js)|Easy|
 784|[Letter Case Permutation](./0784-letter-case-permutation.js)|Medium|
 790|[Domino and Tromino Tiling](./0790-domino-and-tromino-tiling.js)|Medium|