54 lines
1.6 KiB
Swift
54 lines
1.6 KiB
Swift
func findNode(from start: Int, of graph: [[(node: Int, weight: Int)]]) -> (node: Int, length: Int) {
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var result = (node: start, length: 0)
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var visited = Array(repeating: false, count: graph.count)
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var stack = [(node: Int, length: Int)]()
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stack.append(result)
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visited[start] = true
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while !stack.isEmpty {
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if let (now, cur_len) = stack.popLast()
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{
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if cur_len > result.length {
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result = (node: now, length: cur_len)
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}
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for next in graph[now] {
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if !visited[next.node] {
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visited[next.node] = true
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stack.append((node: next.node, length: cur_len + next.weight))
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}
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}
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}
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}
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return result
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}
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if let N = Int(readLine() ?? "0")
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{
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if N == 1 {
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print(0)
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}
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else {
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var graph = Array(repeating: [(node: Int, weight: Int)](), count: N+1)
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for _ in 0..<N-1 {
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if let line = readLine(),
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let data = line.split(separator: " ").compactMap({Int($0)}) as? [Int],
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data.count == 3
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{
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let parent = data[0]
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let child = data[1]
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let weight = data[2]
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graph[parent].append((node: child, weight: weight))
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graph[child].append((node: parent, weight: weight))
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}
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}
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let startNode: Int = findNode(from: 1, of: graph).node
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print(findNode(from: startNode, of: graph).length)
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}
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}
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