DP-Algo

Algorithm/DP-DynamicProgramming/Tree-DP/树的直径-最远点对.cpp

@@ -0,0 +1,60 @@
+#include <iostream>
+#include <vector>
+#include <algorithm>
+using namespace std;
+vector<vector<int>> adj;
+vector<int> dp;
+void dfs(int v, int parent){
+	//no return;
+	for(auto x : adj[v]){
+		if(x == parent) continue;
+		dfs(x, v);
+		dp[v] = max(dp[v], dp[x] + 1);
+	}
+}
+
+int main(){
+	int n;
+	cin >> n;
+	adj.resize(n, vector<int>());
+	dp.resize(n, 1);
+	vector<bool> visited(n, false);
+	//<2F><><EFBFBD><EFBFBD><EFBFBD>ڵ<EFBFBD><DAB5><EFBFBD>0<EFBFBD><30>ʼ<EFBFBD><CABC>n - 1 
+	for(int i = 0; i < n - 1; i++){
+		int a, b;
+		cin >> a >> b;
+		adj[a].push_back(b);
+		adj[b].push_back(a);
+	}
+	dfs(0, -1);
+	int mmax = 0;
+	if(adj[0].size() == 1) cout << dp[0] << endl;
+	else{
+		vector<int> tmp;
+		for(auto x : adj[0]){
+			tmp.push_back(dp[x]);
+		}
+		sort(tmp.begin(), tmp.end());
+		mmax = *(tmp.end() - 1) + *(tmp.end() - 2);
+		cout << mmax + 1<< endl;
+	}
+	return 0;
+}
+/*
+7
+0 1
+0 2
+1 3
+1 4
+2 5
+2 6
+
+8
+0 1
+0 2
+1 3
+1 4
+2 5
+2 6
+3 7
+*/