51 lines
1.1 KiB
C++
51 lines
1.1 KiB
C++
#include <iostream>
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#include <utility>
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#include <vector>
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using namespace std;
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void dfs(vector<vector<int>>& d, const vector<vector<int>>& adj_, vector<bool>& vs, int v){
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d[v][0] = 0;
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d[v][1] = 1;
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for(auto x : adj_[v]){
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if(vs[x] == false) {
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vs[x] = true;
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dfs(d, adj_, vs, x);
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//回溯
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d[v][0] += max(d[x][0], d[x][1]); // 不选u，子树可自由选
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d[v][1] += d[x][0]; // 选u，子树必须不选根
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}
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}
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}
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int main(){
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//图的话直接用vector存邻接表即可
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int n;
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cin >> n;
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vector<vector<int>> adj(n);
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vector<vector<int>> dp(n, vector<int>(2, 0));
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vector<bool> visited(n, false);
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//vector<vector<int>> choose(n, vector<int>(n, 0));
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//这里节点从0开始到n - 1
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for(int i = 0; i < n - 1; i++){
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int a, b;
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cin >> a >> b;
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adj[a].push_back(b);
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adj[b].push_back(a);
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}
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/*
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for(int l = 2; l <= n; l++){
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for(int i = 0; i < n - l + 1; i++){
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int j = i + l - 1;
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for(int k = i; k < j; k++){
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if(adj[i][j])
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d[i][j] = max(dp[i][j], )
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}
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}
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}*/
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visited[0] = true;
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dfs(dp, adj, visited, 0); // 以0为根
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cout << max(dp[0][0], dp[0][1]) << endl;
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return 0;
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}
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