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Author: koralkulacoglu

LeetCode/3434-find-the-number-of-distinct-colors-among-the-balls/README.md

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+<p>You are given an integer <code>limit</code> and a 2D array <code>queries</code> of size <code>n x 2</code>.</p>
+
+<p>There are <code>limit + 1</code> balls with <strong>distinct</strong> labels in the range <code>[0, limit]</code>. Initially, all balls are uncolored. For every query in <code>queries</code> that is of the form <code>[x, y]</code>, you mark ball <code>x</code> with the color <code>y</code>. After each query, you need to find the number of colors among the balls.</p>
+
+<p>Return an array <code>result</code> of length <code>n</code>, where <code>result[i]</code> denotes the number of colors <em>after</em> <code>i<sup>th</sup></code> query.</p>
+
+<p><strong>Note</strong> that when answering a query, lack of a color <em>will not</em> be considered as a color.</p>
+
+<p>&nbsp;</p>
+<p><strong class="example">Example 1:</strong></p>
+
+<div class="example-block">
+<p><strong>Input:</strong> <span class="example-io">limit = 4, queries = [[1,4],[2,5],[1,3],[3,4]]</span></p>
+
+<p><strong>Output:</strong> <span class="example-io">[1,2,2,3]</span></p>
+
+<p><strong>Explanation:</strong></p>
+
+<p><img alt="" src="https://assets.leetcode.com/uploads/2024/04/17/ezgifcom-crop.gif" style="width: 455px; height: 145px;" /></p>
+
+<ul>
+	<li>After query 0, ball 1 has color 4.</li>
+	<li>After query 1, ball 1 has color 4, and ball 2 has color 5.</li>
+	<li>After query 2, ball 1 has color 3, and ball 2 has color 5.</li>
+	<li>After query 3, ball 1 has color 3, ball 2 has color 5, and ball 3 has color 4.</li>
+</ul>
+</div>
+
+<p><strong class="example">Example 2:</strong></p>
+
+<div class="example-block">
+<p><strong>Input:</strong> <span class="example-io">limit = 4, queries = [[0,1],[1,2],[2,2],[3,4],[4,5]]</span></p>
+
+<p><strong>Output:</strong> <span class="example-io">[1,2,2,3,4]</span></p>
+
+<p><strong>Explanation:</strong></p>
+
+<p><strong><img alt="" src="https://assets.leetcode.com/uploads/2024/04/17/ezgifcom-crop2.gif" style="width: 457px; height: 144px;" /></strong></p>
+
+<ul>
+	<li>After query 0, ball 0 has color 1.</li>
+	<li>After query 1, ball 0 has color 1, and ball 1 has color 2.</li>
+	<li>After query 2, ball 0 has color 1, and balls 1 and 2 have color 2.</li>
+	<li>After query 3, ball 0 has color 1, balls 1 and 2 have color 2, and ball 3 has color 4.</li>
+	<li>After query 4, ball 0 has color 1, balls 1 and 2 have color 2, ball 3 has color 4, and ball 4 has color 5.</li>
+</ul>
+</div>
+
+<p>&nbsp;</p>
+<p><strong>Constraints:</strong></p>
+
+<ul>
+	<li><code>1 &lt;= limit &lt;= 10<sup>9</sup></code></li>
+	<li><code>1 &lt;= n == queries.length &lt;= 10<sup>5</sup></code></li>
+	<li><code>queries[i].length == 2</code></li>
+	<li><code>0 &lt;= queries[i][0] &lt;= limit</code></li>
+	<li><code>1 &lt;= queries[i][1] &lt;= 10<sup>9</sup></code></li>
+</ul>

LeetCode/3434-find-the-number-of-distinct-colors-among-the-balls/solution.cpp

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+class Solution {
+public:
+    vector<int> queryResults(int limit, vector<vector<int>>& queries) {
+        unordered_map<int, int> color, freq;
+        int colors = 0;
+        vector<int> res;
+        for (vector<int>& query : queries) {
+            int x = query[0];
+            int y = query[1];
+
+            int prevCol = color[x];
+            if (prevCol == 0) {
+                color[x] = y;
+                freq[y]++;
+                if (freq[y] == 1) colors++;
+            }
+            else if (prevCol != y) {
+                color[x] = y;
+                freq[prevCol]--;
+                freq[y]++;
+                if (freq[prevCol] == 0) colors--;
+                if (freq[y] == 1) colors++;
+            }
+
+            res.push_back(colors);
+        }
+
+        return res;
+    }
+};