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| 1 | +<h2><a href="https://leetcode.com/problems/largest-color-value-in-a-directed-graph">1986. Largest Color Value in a Directed Graph</a></h2><h3>Hard</h3><hr><p>There is a <strong>directed graph</strong> of <code>n</code> colored nodes and <code>m</code> edges. The nodes are numbered from <code>0</code> to <code>n - 1</code>.</p> |
| 2 | + |
| 3 | +<p>You are given a string <code>colors</code> where <code>colors[i]</code> is a lowercase English letter representing the <strong>color</strong> of the <code>i<sup>th</sup></code> node in this graph (<strong>0-indexed</strong>). You are also given a 2D array <code>edges</code> where <code>edges[j] = [a<sub>j</sub>, b<sub>j</sub>]</code> indicates that there is a <strong>directed edge</strong> from node <code>a<sub>j</sub></code> to node <code>b<sub>j</sub></code>.</p> |
| 4 | + |
| 5 | +<p>A valid <strong>path</strong> in the graph is a sequence of nodes <code>x<sub>1</sub> -> x<sub>2</sub> -> x<sub>3</sub> -> ... -> x<sub>k</sub></code> such that there is a directed edge from <code>x<sub>i</sub></code> to <code>x<sub>i+1</sub></code> for every <code>1 <= i < k</code>. The <strong>color value</strong> of the path is the number of nodes that are colored the <strong>most frequently</strong> occurring color along that path.</p> |
| 6 | + |
| 7 | +<p>Return <em>the <strong>largest color value</strong> of any valid path in the given graph, or </em><code>-1</code><em> if the graph contains a cycle</em>.</p> |
| 8 | + |
| 9 | +<p> </p> |
| 10 | +<p><strong class="example">Example 1:</strong></p> |
| 11 | + |
| 12 | +<p><img alt="" src="https://assets.leetcode.com/uploads/2021/04/21/leet1.png" style="width: 400px; height: 182px;" /></p> |
| 13 | + |
| 14 | +<pre> |
| 15 | +<strong>Input:</strong> colors = "abaca", edges = [[0,1],[0,2],[2,3],[3,4]] |
| 16 | +<strong>Output:</strong> 3 |
| 17 | +<strong>Explanation:</strong> The path 0 -> 2 -> 3 -> 4 contains 3 nodes that are colored <code>"a" (red in the above image)</code>. |
| 18 | +</pre> |
| 19 | + |
| 20 | +<p><strong class="example">Example 2:</strong></p> |
| 21 | + |
| 22 | +<p><img alt="" src="https://assets.leetcode.com/uploads/2021/04/21/leet2.png" style="width: 85px; height: 85px;" /></p> |
| 23 | + |
| 24 | +<pre> |
| 25 | +<strong>Input:</strong> colors = "a", edges = [[0,0]] |
| 26 | +<strong>Output:</strong> -1 |
| 27 | +<strong>Explanation:</strong> There is a cycle from 0 to 0. |
| 28 | +</pre> |
| 29 | + |
| 30 | +<p> </p> |
| 31 | +<p><strong>Constraints:</strong></p> |
| 32 | + |
| 33 | +<ul> |
| 34 | + <li><code>n == colors.length</code></li> |
| 35 | + <li><code>m == edges.length</code></li> |
| 36 | + <li><code>1 <= n <= 10<sup>5</sup></code></li> |
| 37 | + <li><code>0 <= m <= 10<sup>5</sup></code></li> |
| 38 | + <li><code>colors</code> consists of lowercase English letters.</li> |
| 39 | + <li><code>0 <= a<sub>j</sub>, b<sub>j</sub> < n</code></li> |
| 40 | +</ul> |
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