Samsung-Graph Coloring

#include <iostream>

using namespace std;

// Given an undirected connected graph. Color the vertices of the graph with two colors, such that adjacent vertices have different colors. Return the number of vertices colored with 0. If coloring is not possible, return -1.
// Input:
// 8 8
// 1 4
// 4 0
// 4 3
// 1 2
// 2 3
// 2 5
// 7 6
// 5 7

// Output:
// 5

int n, m, x, y, l, f, c;
int g[10][10];
int color[10];

int bfs(){
    for(int i=0; i<n; ++i)
        color[i] = -1;
    int q[100];
    for(int k=0; k<n; ++k){
        f = 0;
        l = 0;
        if(color[k] == -1){
            q[l++] = k;
            color[k] = 0;
        }
        while(f < l){
            x = q[f++];
            c = color[x];
            for(int i=0; i<n; ++i){
                if(g[x][i]){
                    if(color[i] == -1){
                        color[i] = !c;
                        q[l++] = i;
                    }
                    else if(color[i] == c)
                        return -1;
                }
            }
        }
    }
    int sum = 0;
    for(int i=0; i<n; ++i)
        if(!color[i])
            sum += 1;
    return sum;
}

int main() {
    cin>>n>>m;
    for(int i=0; i<m; ++i){
        cin>>x>>y;
        g[x][y] = 1;
        g[y][x] = 1;
    }
    cout<<bfs();
    return 0;
}