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54 lines
3.9 KiB
HTML
54 lines
3.9 KiB
HTML
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<p>There is an undirected weighted graph with <code>n</code> vertices labeled from <code>0</code> to <code>n - 1</code>.</p>
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<p>You are given the integer <code>n</code> and an array <code>edges</code>, where <code>edges[i] = [u<sub>i</sub>, v<sub>i</sub>, w<sub>i</sub>]</code> indicates that there is an edge between vertices <code>u<sub>i</sub></code> and <code>v<sub>i</sub></code> with a weight of <code>w<sub>i</sub></code>.</p>
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<p>A walk on a graph is a sequence of vertices and edges. The walk starts and ends with a vertex, and each edge connects the vertex that comes before it and the vertex that comes after it. It's important to note that a walk may visit the same edge or vertex more than once.</p>
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<p>The <strong>cost</strong> of a walk starting at node <code>u</code> and ending at node <code>v</code> is defined as the bitwise <code>AND</code> of the weights of the edges traversed during the walk. In other words, if the sequence of edge weights encountered during the walk is <code>w<sub>0</sub>, w<sub>1</sub>, w<sub>2</sub>, ..., w<sub>k</sub></code>, then the cost is calculated as <code>w<sub>0</sub> & w<sub>1</sub> & w<sub>2</sub> & ... & w<sub>k</sub></code>, where <code>&</code> denotes the bitwise <code>AND</code> operator.</p>
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<p>You are also given a 2D array <code>query</code>, where <code>query[i] = [s<sub>i</sub>, t<sub>i</sub>]</code>. For each query, you need to find the minimum cost of the walk starting at vertex <code>s<sub>i</sub></code> and ending at vertex <code>t<sub>i</sub></code>. If there exists no such walk, the answer is <code>-1</code>.</p>
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<p>Return <em>the array </em><code>answer</code><em>, where </em><code>answer[i]</code><em> denotes the <strong>minimum</strong> cost of a walk for query </em><code>i</code>.</p>
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<p> </p>
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<p><strong class="example">Example 1:</strong></p>
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<div class="example-block">
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<p><strong>Input:</strong> <span class="example-io">n = 5, edges = [[0,1,7],[1,3,7],[1,2,1]], query = [[0,3],[3,4]]</span></p>
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<p><strong>Output:</strong> <span class="example-io">[1,-1]</span></p>
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<p><strong>Explanation:</strong></p>
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<img alt="" src="https://assets.leetcode.com/uploads/2024/01/31/q4_example1-1.png" style="padding: 10px; background: rgb(255, 255, 255); border-radius: 0.5rem; width: 351px; height: 141px;" />
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<p>To achieve the cost of 1 in the first query, we need to move on the following edges: <code>0->1</code> (weight 7), <code>1->2</code> (weight 1), <code>2->1</code> (weight 1), <code>1->3</code> (weight 7).</p>
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<p>In the second query, there is no walk between nodes 3 and 4, so the answer is -1.</p>
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<p><strong class="example">Example 2:</strong></p>
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</div>
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<div class="example-block">
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<p><strong>Input:</strong> <span class="example-io">n = 3, edges = [[0,2,7],[0,1,15],[1,2,6],[1,2,1]], query = [[1,2]]</span></p>
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<p><strong>Output:</strong> <span class="example-io">[0]</span></p>
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<p><strong>Explanation:</strong></p>
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<img alt="" src="https://assets.leetcode.com/uploads/2024/01/31/q4_example2e.png" style="padding: 10px; background: rgb(255, 255, 255); border-radius: 0.5rem; width: 211px; height: 181px;" />
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<p>To achieve the cost of 0 in the first query, we need to move on the following edges: <code>1->2</code> (weight 1), <code>2->1</code> (weight 6), <code>1->2</code> (weight 1).</p>
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</div>
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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 <= 10<sup>5</sup></code></li>
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<li><code>0 <= edges.length <= 10<sup>5</sup></code></li>
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<li><code>edges[i].length == 3</code></li>
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<li><code>0 <= u<sub>i</sub>, v<sub>i</sub> <= n - 1</code></li>
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<li><code>u<sub>i</sub> != v<sub>i</sub></code></li>
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<li><code>0 <= w<sub>i</sub> <= 10<sup>5</sup></code></li>
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<li><code>1 <= query.length <= 10<sup>5</sup></code></li>
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<li><code>query[i].length == 2</code></li>
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<li><code>0 <= s<sub>i</sub>, t<sub>i</sub> <= n - 1</code></li>
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</ul>
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