Add solution #947

Author: JoshCrozier

README.md

@@ -1,4 +1,4 @@
-# 1,031 LeetCode solutions in JavaScript
+# 1,032 LeetCode solutions in JavaScript
 
 [https://leetcode.com/](https://leetcode.com/)
 
@@ -756,6 +756,7 @@
 944|[Delete Columns to Make Sorted](./solutions/0944-delete-columns-to-make-sorted.js)|Easy|
 945|[Minimum Increment to Make Array Unique](./solutions/0945-minimum-increment-to-make-array-unique.js)|Medium|
 946|[Validate Stack Sequences](./solutions/0946-validate-stack-sequences.js)|Medium|
+947|[Most Stones Removed with Same Row or Column](./solutions/0947-most-stones-removed-with-same-row-or-column.js)|Medium|
 966|[Vowel Spellchecker](./solutions/0966-vowel-spellchecker.js)|Medium|
 970|[Powerful Integers](./solutions/0970-powerful-integers.js)|Easy|
 976|[Largest Perimeter Triangle](./solutions/0976-largest-perimeter-triangle.js)|Easy|

solutions/0947-most-stones-removed-with-same-row-or-column.js

@@ -0,0 +1,61 @@
+/**
+ * 947. Most Stones Removed with Same Row or Column
+ * https://leetcode.com/problems/most-stones-removed-with-same-row-or-column/
+ * Difficulty: Medium
+ *
+ * On a 2D plane, we place n stones at some integer coordinate points. Each coordinate point may
+ * have at most one stone.
+ *
+ * A stone can be removed if it shares either the same row or the same column as another stone
+ * that has not been removed.
+ *
+ * Given an array stones of length n where stones[i] = [xi, yi] represents the location of the
+ * ith stone, return the largest possible number of stones that can be removed.
+ */
+
+/**
+ * @param {number[][]} stones
+ * @return {number}
+ */
+var removeStones = function(stones) {
+  const parent = new Map();
+  const find = (stoneIndex) => {
+    if (!parent.has(stoneIndex)) {
+      parent.set(stoneIndex, stoneIndex);
+    }
+    if (parent.get(stoneIndex) !== stoneIndex) {
+      parent.set(stoneIndex, find(parent.get(stoneIndex)));
+    }
+    return parent.get(stoneIndex);
+  };
+
+  const union = (stone1, stone2) => {
+    parent.set(find(stone1), find(stone2));
+  };
+
+  const stoneMap = new Map();
+  for (let i = 0; i < stones.length; i++) {
+    const [row, col] = stones[i];
+    const rowKey = `r${row}`;
+    const colKey = `c${col}`;
+
+    if (stoneMap.has(rowKey)) {
+      union(i, stoneMap.get(rowKey));
+    } else {
+      stoneMap.set(rowKey, i);
+    }
+
+    if (stoneMap.has(colKey)) {
+      union(i, stoneMap.get(colKey));
+    } else {
+      stoneMap.set(colKey, i);
+    }
+  }
+
+  const uniqueGroups = new Set();
+  for (let i = 0; i < stones.length; i++) {
+    uniqueGroups.add(find(i));
+  }
+
+  return stones.length - uniqueGroups.size;
+};