Add solution #781

Author: JoshCrozier

README.md

@@ -591,6 +591,7 @@
 778|[Swim in Rising Water](./0778-swim-in-rising-water.js)|Hard|
 779|[K-th Symbol in Grammar](./0779-k-th-symbol-in-grammar.js)|Medium|
 780|[Reaching Points](./0780-reaching-points.js)|Hard|
+781|[Rabbits in Forest](./0781-rabbits-in-forest.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|

solutions/0781-rabbits-in-forest.js

@@ -0,0 +1,36 @@
+/**
+ * 781. Rabbits in Forest
+ * https://leetcode.com/problems/rabbits-in-forest/
+ * Difficulty: Medium
+ *
+ * There is a forest with an unknown number of rabbits. We asked n rabbits "How many rabbits have
+ * the same color as you?" and collected the answers in an integer array answers where answers[i]
+ * is the answer of the ith rabbit.
+ *
+ * Given the array answers, return the minimum number of rabbits that could be in the forest.
+ */
+
+/**
+ * @param {number[]} answers
+ * @return {number}
+ */
+var numRabbits = function(answers) {
+  const colorGroups = {};
+  let totalRabbits = 0;
+
+  for (const answer of answers) {
+    if (answer === 0) {
+      totalRabbits++;
+      continue;
+    }
+
+    if (!colorGroups[answer] || colorGroups[answer] === 0) {
+      totalRabbits += answer + 1;
+      colorGroups[answer] = answer;
+    } else {
+      colorGroups[answer]--;
+    }
+  }
+
+  return totalRabbits;
+};