Need help for 'Tree Distance Set' problem of Starters 126

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Problem: Tree Distance Set Practice Coding Problem - CodeChef

I wrote code implementing the approach (half of the diameter red color and the rest blue, after that color the half of the remaining as blue and the rest red). The problem is this passed the initial test case described in the problem statement. But showing wrong answers for the remaining test cases. Can anyone help me to detect the issue in my code?

My Code:

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

int n;
vector<vector<int>> graph;
vector<int> diameter;
void inputTree()
{
    cin >> n;
    int e = n - 1;

    graph.resize(n, vector<int>());
    while (e--)
    {
        int a, b;
        cin >> a >> b;
        a--, b--;
        graph[a].push_back(b);
        graph[b].push_back(a);
    }
}

int getLeaf(int src)
{
    int dis[n] = {-1}, vis[n] = {0};

    queue<int> qu;
    qu.push(src);
    dis[src] = 0;
    vis[src] = 1;

    while (!qu.empty())
    {
        int u = qu.front();
        qu.pop();

        for (int v : graph[u])
        {
            if (vis[v] != 1)
            {
                vis[v] = 1;
                dis[v] = dis[u] + 1;
                qu.push(v);
            }
        }
    }

    int leaf = src;
    for (int i = 0; i < n; i++)
        if (dis[leaf] < dis[i])
            leaf = i;

    return leaf;
}

bool found = 0;
void getDiameter(int src, int des, int par)
{
    if (found)
        return;

    diameter.push_back(src);

    if (src == des)
        found = 1;

    for (int v : graph[src])
    {
        if (v != par)
            getDiameter(v, des, src);
    }

    if (!found)
        diameter.pop_back();
}

void solve()
{
    // 0. Take I/O
    inputTree();

    // 1. Get Diameter of the Tree
    int leaf1 = getLeaf(0);
    int leaf2 = getLeaf(leaf1);
    getDiameter(leaf1, leaf2, -1);


    // 2. Color Half of the Diameter with Red and rest Blue
    int coloring[n];
    int vis[n] = {0};

    for (int i = 0; i < diameter.size(); i++)
    {
        int node = diameter[i];
        if (i <= diameter.size() / 2)
            coloring[node] = 1;
        else
            coloring[node] = 0;

        vis[node] = 1;
    }


    // 3. Color Remaing nodes (half of them are Blue and rest Red)
    vector<int> remainging;
    for (int i = 0; i < n; i++)
        if (vis[i] == 0)
            remainging.push_back(i);

    for (int i = 0; i < remainging.size(); i++)
    {
        int node = remainging[i];
        if (i <= remainging.size())
            coloring[node] = 0;
        else
            coloring[node] = 1;
    }

    // 4. Pring Color
    for (int i = 0; i < n; i++)
    {
        if (coloring[i])
            cout << 'R';
        else
            cout << 'B';
    }
}

int main()
{
    int t;
    cin >> t;

    while (t--)
    {
        solve();
        cout << '\n';
    }

    return 0;
}