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36 lines
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36 lines
1.7 KiB
HTML
<p>You are given a <strong>directed</strong> graph of <code>n</code> nodes numbered from <code>0</code> to <code>n - 1</code>, where each node has <strong>at most one</strong> outgoing edge.</p>
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<p>The graph is represented with a given <strong>0-indexed</strong> array <code>edges</code> of size <code>n</code>, indicating that there is a directed edge from node <code>i</code> to node <code>edges[i]</code>. If there is no outgoing edge from node <code>i</code>, then <code>edges[i] == -1</code>.</p>
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<p>Return <em>the length of the <strong>longest</strong> cycle in the graph</em>. If no cycle exists, return <code>-1</code>.</p>
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<p>A cycle is a path that starts and ends at the <strong>same</strong> node.</p>
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<p> </p>
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<p><strong>Example 1:</strong></p>
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<img alt="" src="https://assets.leetcode.com/uploads/2022/06/08/graph4drawio-5.png" style="width: 335px; height: 191px;" />
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<pre>
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<strong>Input:</strong> edges = [3,3,4,2,3]
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<strong>Output:</strong> 3
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<strong>Explanation:</strong> The longest cycle in the graph is the cycle: 2 -> 4 -> 3 -> 2.
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The length of this cycle is 3, so 3 is returned.
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</pre>
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<p><strong>Example 2:</strong></p>
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<img alt="" src="https://assets.leetcode.com/uploads/2022/06/07/graph4drawio-1.png" style="width: 171px; height: 161px;" />
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<pre>
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<strong>Input:</strong> edges = [2,-1,3,1]
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<strong>Output:</strong> -1
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<strong>Explanation:</strong> There are no cycles in this graph.
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</pre>
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<p> </p>
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<p><strong>Constraints:</strong></p>
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<ul>
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<li><code>n == edges.length</code></li>
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<li><code>2 <= n <= 10<sup>5</sup></code></li>
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<li><code>-1 <= edges[i] < n</code></li>
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<li><code>edges[i] != i</code></li>
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</ul>
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