Language: C++

#include <iostream>
#include <algorithm> // next_permutation
#include <iomanip>
#include <cmath>
#include <vector>
#include <sstream>
#include <string>
#include <cstdio>
#include <stack>
#include <queue>
#include <list>
#include <numeric> //accumulate
//#include <unordered_map> //???????????\??¢??°
#include <fstream> //ifstream, ofstream

//#define NDEBUG //NDEBUG???#include <cassert>???????????????????????????????????´???assert?????????????????????????????????NDEBUG?????????????????????????????????????????????
#include <cassert> //assert


using namespace std;

//???????????°??????TEST????????????????????¬???????????????????????????????????¢????????????
#define TEST //*******************************************************************************************************************************************
//?????????????????¨??§?????\????????????????????????????????°?????????????¨???????????????????dout???????????????????????§???????????¬??????????????????????????????????????????
//??????????????????????????????????????????????????????????§?CPU???????£??????????????????§???TLE?????????????????????????????????????????§????????¨???                           ????????????????????????cerr????????£????????????????????????????????????
#ifdef TEST
#define dout cout
#define din cin
#else
stringstream dummy; //???????????°??????dout?????????????????????????????????
#define dout dummy.str(""); dummy.clear(stringstream::goodbit); dummy //dummy?????????????????????????????????????????¨?????¢?????¢???????????????
//???????????¨??????????????????goodbit?????????????????????????????¨???????????´????????????????????????????????¨?????°?????????????????§???????????????????????????????????? http://d.hatena.ne.jp/linden/20060427/p1
#endif

//?¨??????????????????????????????????????????????????????´??????OUTPUTFILE????????????????????¬???????????????????????????????????¢????????????
//#define OUTPUTFILE "output.txt" //*******************************************************************************************************************************************
#ifdef OUTPUTFILE
#define dout outputfile //??¨????????????TLE????????§?????????dout?????¨??¨??????????????¢????????????????????????????????????????????§????¨????????????´??????????????£??????????????????????¨?????????????????????????????????????????????§?????????????????????
ofstream outputfile(OUTPUTFILE);
#define OutputFilePath "/Users/Nag/Documents/Prgm/Test/DerivedData/Test/Build/Products/Debug/output.txt"
#endif

//?¨??????\???????????????????????????????????????????????´??????INPUTFROMTEXTFILE????????????????????¬???????????????????????????????????¢????????????
//#define INPUTFILE "input.txt" //*******************************************************************************************************************************************
#ifdef INPUTFILE
#define din inputfile
ifstream inputfile(INPUTFILE);
#endif


#define disp(A) dout << #A << " = " << (A) << endl
#define disP(A) dout << setw(3) << (A) << " " // << setw(3) ??????????????\????????????
#define rep(i,a,n) for(int (i)=(a); (i)<(n); (i)++)
#define dispAll(A,n) dout << #A << " = "; rep(j, 0, (n)) {disP(A[j]);} dout << endl

typedef pair<int,int> pii;
typedef vector<int> vi;
typedef unsigned long long ll;


const int INF = 1e9-1;

int N;
const int N_MAX = 100000;

bool edge[N_MAX][N_MAX] = {0};
int color[N_MAX] = {0}; //??£?????°???????????¨???1??\????????°?????§???????????????
int currentColor = 0;



void dfs(int i) { //depth first search
    
    if(color[i]!=0) return; //?????§????¨??????????
    
    //??????????????????????¨??????§????????°?????????????????????????????????????????????????????????dfs????????°??????????????????
    color[i] = currentColor;
    rep(j,0,N) {
        if(edge[i][j]) dfs(j);
    }
    
    //???????????????????????????dfs??????????????????????????????????????£??????
    return;
    
}



int main() {
    int M;
    din>>N>>M;
    
    int v1, v2;
    rep(i,0,M) {
        din>>v1>>v2;
        edge[v1][v2] = edge[v2][v1] = 1;
    }
    
    rep(i,0,N) edge[i][i] = 1;
    
    
    
//    //test display
//    dout<<endl;
//    dout<<"       dist = ";
//    rep(i,0,N) disP(i);
//    dout<<endl;
//    rep(i,0,N) {
//        disP(i); dispAll(edge[i], N);
//    }
//    dout<<endl;
    
//    //test display
//    dout<<"    i = ";
//    rep(i,0,N) disP(i);
//    dout << endl;
//    dispAll(color, N);
    
    
    //execute DFS (Depth First Search)
    //??±???????????¢?´¢??§??¨??????????????¢?´¢?????????????????°?????????????????????????£??????????????????????????????????
    rep(i,0,N) {
        if(color[i]==0) { //?????????????????????????????????dfs
            currentColor++;
            dfs(i);
        }
    }
    
//    //test display
//    dout<<"    i = ";
//    rep(i,0,N) disP(i);
//    dout << endl;
//    dispAll(color, N);
    
    //output
    int Q; din>>Q;
    rep(i,0,Q) {
        din >> v1 >> v2;
        
        dout << (color[v1]==color[v2] ? "yes" : "no") << endl;
    }
    
    
    
#ifdef INPUTFILE
    inputfile.close();
#endif
    
#ifdef OUTPUTFILE
    outputfile.close();
    cout << "\"" << OutputFilePath << "\"" << endl;
#endif
    
    return 0;
}

Compiler output:
/tmp/ccZIVBRo.o: in function `dfs(int)':
a.cc:(.text+0x1b): relocation truncated to fit: R_X86_64_PC32 against symbol `color' defined in .bss section in /tmp/ccZIVBRo.o
a.cc:(.text+0x28): relocation truncated to fit: R_X86_64_PC32 against symbol `currentColor' defined in .bss section in /tmp/ccZIVBRo.o
a.cc:(.text+0x3d): relocation truncated to fit: R_X86_64_PC32 against symbol `color' defined in .bss section in /tmp/ccZIVBRo.o
/tmp/ccZIVBRo.o: in function `main':
a.cc:(.text+0x1b1): relocation truncated to fit: R_X86_64_PC32 against symbol `color' defined in .bss section in /tmp/ccZIVBRo.o
a.cc:(.text+0x1be): relocation truncated to fit: R_X86_64_PC32 against symbol `currentColor' defined in .bss section in /tmp/ccZIVBRo.o
a.cc:(.text+0x1c7): relocation truncated to fit: R_X86_64_PC32 against symbol `currentColor' defined in .bss section in /tmp/ccZIVBRo.o
a.cc:(.text+0x23e): relocation truncated to fit: R_X86_64_PC32 against symbol `color' defined in .bss section in /tmp/ccZIVBRo.o
a.cc:(.text+0x255): relocation truncated to fit: R_X86_64_PC32 against symbol `color' defined in .bss section in /tmp/ccZIVBRo.o
collect2: error: ld returned 1 exit status