题目来源:acwing树的重心
代码:
#include <cstring>
#include <iostream>
#include <algorithm>
using namespace std;
int n;
const int N = 100010, M = N * 2;
int h[N];
int e[M], ne[M];
int idx;
bool st[N];
int ans = N;
void add (int a, int b) {
e[idx] = b;
ne[idx] = h[a];
h[a] = idx; //h[a] = idx++;
idx++;
}
int dfs (int u) {
st[u] = true;
int sum = 1, res = 0;
for (int i = h[u]; i != -1; i = ne[i]) {
int j = e[i];
if (st[j] == false) {
int s = dfs(j);
res = max (res, s);
sum += s;
}
}
res = max (res, n - sum);
ans = min(ans, res);
return sum;
}
int main() {
memset(h, -1, sizeof h);
cin >> n;
for (int i = 0; i < n - 1; i++) {
int a, b;
cin >> a >> b;
add (a, b), add (b, a);
}
dfs(1);
cout << ans << endl;
}
/*
input
9
1 2
1 7
1 4
2 8
2 5
4 3
3 9
4 6
output
4
*/
请帮忙解释一下dfs函数以及三个变量ans、res、sum的含义
当我在VScode中调试时,我因该怎么设置断点监视这三个变量?