2374. Node With Highest Edge Score
Description
You are given a directed graph with n
nodes labeled from 0
to n - 1
, where each node has exactly one outgoing edge.
The graph is represented by a given 0-indexed integer array edges
of length n
, where edges[i]
indicates that there is a directed edge from node i
to node edges[i]
.
The edge score of a node i
is defined as the sum of the labels of all the nodes that have an edge pointing to i
.
Return the node with the highest edge score. If multiple nodes have the same edge score, return the node with the smallest index.
Example 1:
Input: edges = [1,0,0,0,0,7,7,5] Output: 7 Explanation: - The nodes 1, 2, 3 and 4 have an edge pointing to node 0. The edge score of node 0 is 1 + 2 + 3 + 4 = 10. - The node 0 has an edge pointing to node 1. The edge score of node 1 is 0. - The node 7 has an edge pointing to node 5. The edge score of node 5 is 7. - The nodes 5 and 6 have an edge pointing to node 7. The edge score of node 7 is 5 + 6 = 11. Node 7 has the highest edge score so return 7.
Example 2:
Input: edges = [2,0,0,2] Output: 0 Explanation: - The nodes 1 and 2 have an edge pointing to node 0. The edge score of node 0 is 1 + 2 = 3. - The nodes 0 and 3 have an edge pointing to node 2. The edge score of node 2 is 0 + 3 = 3. Nodes 0 and 2 both have an edge score of 3. Since node 0 has a smaller index, we return 0.
Constraints:
n == edges.length
2 <= n <= 105
0 <= edges[i] < n
edges[i] != i
Solutions
Solution 1: Single Traversal
We define an array $\textit{cnt}$ of length $n$, where $\textit{cnt}[i]$ represents the edge score of node $i$. Initially, all elements are $0$. We also define an answer variable $\textit{ans}$, initially set to $0$.
Next, we traverse the array $\textit{edges}$. For each node $i$ and its outgoing edge node $j$, we update $\textit{cnt}[j]$ to $\textit{cnt}[j] + i$. If $\textit{cnt}[\textit{ans}] < \textit{cnt}[j]$ or $\textit{cnt}[\textit{ans}] = \textit{cnt}[j]$ and $j < \textit{ans}$, we update $\textit{ans}$ to $j$.
Finally, return $\textit{ans}$.
The time complexity is $O(n)$, and the space complexity is $O(n)$. Here, $n$ is the length of the array $\textit{edges}$.
1 2 3 4 5 6 7 8 9 |
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1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 |
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1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 |
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1 2 3 4 5 6 7 8 9 10 |
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1 2 3 4 5 6 7 8 9 10 11 12 13 |
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