牛客小bai月赛39 F 孤独(dp)
作者:互联网
牛客小白月赛39 F 孤独
#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
int ans = INT_MAX, n;
int sz[1000006];
int dp[1000006];
vector<int>vec[1000006];
void dfs(int i, int fa) {
sz[i] = 1;
int mx1 = 0;
int mx2 = 0;
int mx3 = 0; //第三大的子树
for (auto j : vec[i]) {
if (j == fa)continue;
dfs(j, i);
sz[i] += sz[j];
if (sz[j] > sz[mx1]) {
mx3 = mx2;
mx2 = mx1;
mx1 = j;
} else if (sz[j] > sz[mx2]) {
mx3 = mx2;
mx2 = j;
} else if (sz[j] > sz[mx3]) {
mx3 = j;
}
dp[i] = max(dp[mx1], sz[mx2]);
}
ans = min(ans, max(n - sz[i], max(dp[mx1], max(dp[mx2], sz[mx3]))));
}
int main() {
int i, j, x, y;
scanf("%d", &n);
for (i = 1; i < n; i++) {
scanf("%d%d", &x, &y);
vec[x].push_back(y);
vec[y].push_back(x);
}
dfs(1, 0);
printf("%d\n", ans);
return 0;
}
标签:月赛,39,sz,int,mx2,mx3,mx1,牛客,dp 来源: https://blog.csdn.net/qq_52093121/article/details/121040774