Go: package main

import (
	"bufio"
	"os"
	"strings"
	"strconv"
	"reflect"
	"fmt"
)

var scanner = bufio.NewScanner(os.Stdin)

func scanBoard() [][]int {
	ret := make([][]int, 8)
	for k := range ret {
		ret[k] = make([]int, 8)
		for l := range ret[k] {
			ret[k][l] = 0
		}
	}
	for i := 0; i < 8; i++ {
		scanner.Scan()
		row := strings.Split(scanner.Text(), "")
		for j := 0; j < 8; j++ {
			ret[i][j], _ = strconv.Atoi(row[j])
		}
	}
	return ret
}

func main() {
	for {
		var board [][]int
		var ans string
		if board = scanBoard(); reflect.DeepEqual(board, [][]int{}) {
			break
		}
		fmt.Println(board)
		for i := 0; i < 7; i++ {
			for j := 0; j < 7; j++ {
				if board[i][j] == 1 && board[i+1][j] == 1 && board[i][j+1] == 1 && board[i+1][j+1] == 1 {
					ans = "A"
				}
			}
		}
		for i := 0; i < 5; i++ {
			for j := 0; j < 8; j++ {
				if board[i][j] == 1 && board[i+1][j] == 1 && board[i+2][j] == 1 && board[i+3][j] == 1 {
					ans = "B"
				}
			}
		}
		for i := 0; i < 8; i++ {
			for j := 0; j < 5; j++ {
				if board[i][j] == 1 && board[i][j+1] == 1 && board[i][j+2] == 1 && board[i][j+3] == 1 {
					ans = "C"
				}
			}
		}
		for i := 0; i < 6; i++ {
			for j := 0; j < 7; j++ {
				if board[i][j+1] == 1 && board[i+1][j] == 1 && board[i+1][j+1] == 1 && board[i+2][j] == 1 {
					ans = "D"
				}
			}
		}
		for i := 0; i < 7; i++ {
			for j := 0; j < 6; j++ {
				if board[i][j] == 1 && board[i][j+1] == 1 && board[i+1][j+1] == 1 && board[i+1][j+2] == 1 {
					ans = "E"
				}
			}
		}
		for i := 0; i < 7; i++ {
			for j := 0; j < 6; j++ {
				if board[i][j+1] == 1 && board[i][j+2] == 1 && board[i+1][j] == 1 && board[i+1][j+1] == 1 {
					ans = "G"
				}
			}
		}
		for i := 0; i < 6; i++ {
			for j := 0; j < 7; j++ {
				if board[i][j] == 1 && board[i+1][j] == 1 && board[i+1][j+1] == 1 && board[i+2][j+1] == 1 {
					ans = "F"
				}
			}
		}
		fmt.Println(ans)
	}
}

C++: #include <iostream>
#include <string>


int main(int argc,char* argv[]){
		std::string ans[7] ={"1100000011","1000000010000000100000001","1111","1000000110000001","11000000011","100000001100000001","110000011"};
		std::string alpha[7]={"A","B","C","D","E","F","G"};
		std::string prob[8];
		std::string problem;

		while(std::cin >> prob[0]){
						for(int a=1; a < 8; a++){
										std::cin >> prob[a];
						}
						for(int b=0; b < 8; b++){
										problem = problem + prob[b];
						}
						for(int c=0; c < 7; c++){
										std::string::size_type index = problem.find(ans[c]);
										if(index != std::string::npos){
														std::cout << alpha[c] << std::endl;
										}
						}
		}
}

C++: #include <iostream>
#include <cstdio>
#include <vector>
#include <string>
#include <map>
#include <algorithm>
#include <cmath>
#include <numeric>
#include <stack>
using namespace std;

#define REP(i,n) for(int (i)=0; (i)<(n); (i)++)
#define For(i,a,b) for(int (i)=(a); (i)<(b); (i)++)
#define PUSH(n,v) for(int i=0; i<(n); i++) {int j; cin >> j; v.push_back(j);}

bool hasA(int bd[8][8]) {
    for (int i = 0; i < 7; i++) {
        for (int j = 0; j < 7; j++) {
            if (bd[i][j] && bd[i][j+1] && bd[i+1][j] && bd[i+1][j+1]) return true;
        }
    }
    return false;
}

bool hasB(int bd[8][8]) {
    for (int i = 0; i < 5; i++) {
        for (int j = 0; j < 8; j++) {
            if (bd[i][j] && bd[i+1][j] && bd[i+2][j] && bd[i+3][j]) return true;
        }
    }
    return false;
}

bool hasC(int bd[8][8]) {
    for (int i = 0; i < 8; i++) {
        for (int j = 0; j < 5; j++) {
            if (bd[i][j] && bd[i][j+1] && bd[i][j+2] && bd[i][j+3]) return true;
        }
    }
    return false;
}

bool hasD(int bd[8][8]) {
    for (int i = 0; i < 6; i++) {
        for (int j = 0; j < 6; j++) {
            if (bd[i][j+1] && bd[i+1][j] && bd[i+1][j+1] && bd[i+2][j]) return true;
        }
    }
    return false;
}

bool hasE(int bd[8][8]) {
    for (int i = 0; i < 7; i++) {
        for (int j = 0; j < 6; j++) {
            if (bd[i][j] && bd[i][j+1] && bd[i+1][j+1] && bd[i+1][j+2]) return true;
        }
    }
    return false;
}

bool hasF(int bd[8][8]) {
    for (int i = 0; i < 6; i++) {
        for (int j = 0; j < 6; j++) {
            if (bd[i][j] && bd[i+1][j] && bd[i+1][j+1] && bd[i+2][j+1]) return true;
        }
    }
    return false;
}

bool hasG(int bd[8][8]) {
    for (int i = 0; i < 7; i++) {
        for (int j = 0; j < 6; j++) {
            if (bd[i][j+1] && bd[i][j+2] && bd[i+1][j] && bd[i+1][j+1]) return true;
        }
    }
    return false;
}

int main() {
    string s;
    int bd[8][8];
    while(cin >> s) {
        REP(i,8) bd[0][i] = s[i] - '0';
        REP(j,7) {
            cin >> s;
            REP(i,8) bd[j+1][i] = s[i] - '0';
        }
        // input ends
        if (hasA(bd)) cout << "A" << endl;
        else if (hasB(bd)) cout << "B" << endl;
        else if (hasC(bd)) cout << "C" << endl;
        else if (hasD(bd)) cout << "D" << endl;
        else if (hasE(bd)) cout << "E" << endl;
        else if (hasF(bd)) cout << "F" << endl;
        else if (hasG(bd)) cout << "G" << endl;
    }
    return 0;
}

C++: #include<iostream>
using namespace std;
typedef unsigned __int64 ull;
int main(){
	int shape[7]={0x0303,0x01010101,0x0f,
		0x010302,0x0603,0x020301,0x0306};
	while(!cin.eof()){
		int ans=-1;
		ull mass=0;	
		for(int i=0;i<64;i++){
			char c;
			cin>>c;
			if(c=='1')mass |= (ull)1<<i; 
		}
		for(int i=0;i<64;i++){
			for(int j=0;j<7;j++){
				if((mass>>i&shape[j])==shape[j])ans=j;
			}
		}
		cout<<(char)(ans+'A')<<endl;
	}
	return 0;
}

C++: #include <iostream>
#include <string.h>

#define MAX_LINE 8
#define MAXA_DATA 50

using namespace std;

// プロトタイプ宣言
void searchString(string box);

// main関数
int main() {
    int count = 0;
    int max = MAX_LINE * MAXA_DATA;
    char str[8];
    string box;
    for (int i = 0; i < max; i++) {
        cin >> str;
        box.append(str);
        count++;
        // 8行ごとにチェック
        if(count%MAX_LINE == 0){
            searchString(box);
            box = "";
        }
    }
}

// 文字列チェック
void searchString(string box){
    string A("1100000011");
    string B("1000000010000000100000001");
    string C("1111");
    string D("1000000110000001");
    string E("11000000011");
    string F("100000001100000001");
    string G("110000011");
    
    // find関数は文字列がみつからなかったときにnposを返す
    if (box.find(A) != std::string::npos) {
        cout << "A" << endl;
    }
    else if(box.find(B) != std::string::npos) {
        cout << "B" << endl;
    }
    else if(box.find(C) != std::string::npos) {
        cout << "C" << endl;
    }
    else if(box.find(D) != std::string::npos) {
        cout << "D" << endl;
    }
    else if(box.find(E) != std::string::npos) {
        cout << "E" << endl;
    }
    else if(box.find(F) != std::string::npos) {
        cout << "F" << endl;
    }
    else if(box.find(G) != std::string::npos) {
        cout << "G" << endl;
    }
}