Submission #2856108

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Source Code Expand

#include <bits/stdc++.h>
using namespace std;

#define fi first
#define se second
#define mp make_pair
#define pb push_back
typedef long long ll;
typedef pair<int, int> ii;

const int len = 1e5+5;
int block[len], dep[len], sz[len];
vector<int> adj[len];

void fix(int u, int p){
    sz[u] = 1;
    for (int j = 0; j < adj[u].size(); j++){
        int v = adj[u][j];
        if (!block[v] && v != p)
            fix(v, u), sz[u] += sz[v];
    }
}

ii cent(int u, int p, int all){
    ii ans = mp(all, u);
    int mx = all-sz[u];
    for (int j = 0; j < adj[u].size(); j++){
        int v = adj[u][j];
        if (v != p && !block[v])
            ans = min(ans, cent(v, u, all)), mx = max(mx, sz[v]);
    }

    return min(ans, mp(mx, u));
}

void solve(int u, int d){
    fix(u, u);
    u = cent(u, u, sz[u]).se;

    //printf("u = %d, d = %d\n", u, d);

    dep[u] = d;
    block[u] = 1;
    for (int j = 0; j < adj[u].size(); j++){
        int v = adj[u][j];
        if (!block[v])
            solve(v, d+1);
    }
}

int main(){
    int n;
    scanf("%d", &n);
    for (int i = 0; i < n-1; i++){
        int a, b;
        scanf("%d %d", &a, &b);
        adj[a].pb(b);
        adj[b].pb(a);
    }

    solve(1, 0);

    int ans = 0;
    for (int i = 1; i <= n; i++)
        ans = max(ans, dep[i]);

    printf("%d\n", ans);
    return 0;
}

Submission Info

Compile Error

./Main.cpp: In function ‘int main()’:
./Main.cpp:53:20: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result]
     scanf("%d", &n);
                    ^
./Main.cpp:56:31: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result]
         scanf("%d %d", &a, &b);
                               ^

Judge Result