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51 lines
2.7 KiB
HTML
51 lines
2.7 KiB
HTML
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<p>There are <code>n</code> cities connected by some number of flights. You are given an array <code>flights</code> where <code>flights[i] = [from<sub>i</sub>, to<sub>i</sub>, price<sub>i</sub>]</code> indicates that there is a flight from city <code>from<sub>i</sub></code> to city <code>to<sub>i</sub></code> with cost <code>price<sub>i</sub></code>.</p>
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<p>You are also given three integers <code>src</code>, <code>dst</code>, and <code>k</code>, return <em><strong>the cheapest price</strong> from </em><code>src</code><em> to </em><code>dst</code><em> with at most </em><code>k</code><em> stops. </em>If there is no such route, return<em> </em><code>-1</code>.</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/2022/03/18/cheapest-flights-within-k-stops-3drawio.png" style="width: 332px; height: 392px;" />
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<pre>
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<strong>Input:</strong> n = 4, flights = [[0,1,100],[1,2,100],[2,0,100],[1,3,600],[2,3,200]], src = 0, dst = 3, k = 1
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<strong>Output:</strong> 700
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<strong>Explanation:</strong>
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The graph is shown above.
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The optimal path with at most 1 stop from city 0 to 3 is marked in red and has cost 100 + 600 = 700.
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Note that the path through cities [0,1,2,3] is cheaper but is invalid because it uses 2 stops.
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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/2022/03/18/cheapest-flights-within-k-stops-1drawio.png" style="width: 332px; height: 242px;" />
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<pre>
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<strong>Input:</strong> n = 3, flights = [[0,1,100],[1,2,100],[0,2,500]], src = 0, dst = 2, k = 1
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<strong>Output:</strong> 200
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<strong>Explanation:</strong>
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The graph is shown above.
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The optimal path with at most 1 stop from city 0 to 2 is marked in red and has cost 100 + 100 = 200.
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</pre>
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<p><strong>Example 3:</strong></p>
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<img alt="" src="https://assets.leetcode.com/uploads/2022/03/18/cheapest-flights-within-k-stops-2drawio.png" style="width: 332px; height: 242px;" />
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<pre>
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<strong>Input:</strong> n = 3, flights = [[0,1,100],[1,2,100],[0,2,500]], src = 0, dst = 2, k = 0
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<strong>Output:</strong> 500
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<strong>Explanation:</strong>
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The graph is shown above.
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The optimal path with no stops from city 0 to 2 is marked in red and has cost 500.
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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>1 <= n <= 100</code></li>
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<li><code>0 <= flights.length <= (n * (n - 1) / 2)</code></li>
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<li><code>flights[i].length == 3</code></li>
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<li><code>0 <= from<sub>i</sub>, to<sub>i</sub> < n</code></li>
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<li><code>from<sub>i</sub> != to<sub>i</sub></code></li>
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<li><code>1 <= price<sub>i</sub> <= 10<sup>4</sup></code></li>
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<li>There will not be any multiple flights between two cities.</li>
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<li><code>0 <= src, dst, k < n</code></li>
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<li><code>src != dst</code></li>
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</ul>
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