Submission #1215882

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Source Code Expand

#include <cstdio>
#include <vector>
static const int MAXN = 1e5 + 4;
static const int LOGN = 18;

int n;
std::vector<int> e[MAXN];

int ans = 0;
int f[MAXN];
void dfs_dp(int u, int p = -1)
{
    int mask = 0, label = 0;
    for (int v : e[u]) if (v != p) {
        dfs_dp(v, u);
        for (int i = label + 1; i < LOGN; ++i)
            if ((f[v] & (1 << i)) && (mask & (1 << i))) label = i;
        mask |= f[v];
    }
    //int label = 8 * sizeof(int) - __builtin_clz(f[u]) - 1;
    while (mask & (1 << label)) ++label;
    f[u] = (1 << label);
    for (int i = label + 1; i < LOGN; ++i)
        if (mask & (1 << i)) f[u] |= (1 << i);
    if (ans < label) ans = label;
}

int main()
{
    scanf("%d", &n);
    int u, v;
    for (int i = 0; i < n - 1; ++i) {
        scanf("%d%d", &u, &v); --u, --v;
        e[u].push_back(v);
        e[v].push_back(u);
    }

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

    return 0;
}

Submission Info

Compile Error

./Main.cpp: In function ‘int main()’:
./Main.cpp:30:20: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result]
     scanf("%d", &n);
                    ^
./Main.cpp:33:30: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result]
         scanf("%d%d", &u, &v); --u, --v;
                              ^

Judge Result