Add solution #3160

Author: JoshCrozier

README.md

@@ -567,6 +567,7 @@
 3105|[Longest Strictly Increasing or Strictly Decreasing Subarray](./3105-longest-strictly-increasing-or-strictly-decreasing-subarray.js)|Easy|
 3110|[Score of a String](./3110-score-of-a-string.js)|Easy|
 3151|[Special Array I](./3151-special-array-i.js)|Easy|
+3160|[Find the Number of Distinct Colors Among the Balls](./3160-find-the-number-of-distinct-colors-among-the-balls.js)|Medium|
 3223|[Minimum Length of String After Operations](./3223-minimum-length-of-string-after-operations.js)|Medium|
 3392|[Count Subarrays of Length Three With a Condition](./3392-count-subarrays-of-length-three-with-a-condition.js)|Easy|
 3396|[Minimum Number of Operations to Make Elements in Array Distinct](./3396-minimum-number-of-operations-to-make-elements-in-array-distinct.js)|Easy|

solutions/3160-find-the-number-of-distinct-colors-among-the-balls.js

@@ -0,0 +1,40 @@
+/**
+ * 3160. Find the Number of Distinct Colors Among the Balls
+ * https://leetcode.com/problems/find-the-number-of-distinct-colors-among-the-balls/
+ * Difficulty: Medium
+ *
+ * You are given an integer limit and a 2D array queries of size n x 2.
+ *
+ * There are limit + 1 balls with distinct labels in the range [0, limit]. Initially,
+ * all balls are uncolored. For every query in queries that is of the form [x, y],
+ * you mark ball x with the color y. After each query, you need to find the number
+ * of distinct colors among the balls.
+ *
+ * Return an array result of length n, where result[i] denotes the number of distinct
+ * colors after ith query.
+ *
+ * Note that when answering a query, lack of a color will not be considered as a color.
+ */
+
+/**
+ * @param {number} limit
+ * @param {number[][]} queries
+ * @return {number[]}
+ */
+var queryResults = function(limit, queries) {
+  const result = [];
+
+  for (let i = 0, colors = new Map(), counts = new Map(); i < queries.length; i++) {
+    const [index, color] = queries[i];
+    if (colors.has(index)) {
+      const prev = colors.get(index);
+      counts.set(prev, counts.get(prev) - 1);
+      if (!counts.get(prev)) counts.delete(prev);
+    }
+    colors.set(index, color);
+    counts.set(color, (counts.get(color) ?? 0) + 1);
+    result.push(counts.size);
+  }
+
+  return result;
+};