Go: package main

import (
	"fmt"
	"math"
	"strconv"
)

// ColorCode is a string like #rrggbb
type ColorCode string

// ColorName is a name of color
type ColorName string

// Color has colorname and colorcode
type Color struct {
	name ColorName
	code ColorCode
}

// ColorTable has default colors
type ColorTable struct {
	colors []Color
}

var (
	colorTable = ColorTable{
		[]Color{
			Color{"black", "#000000"},
			Color{"blue", "#0000ff"},
			Color{"lime", "#00ff00"},
			Color{"aqua", "#00ffff"},
			Color{"red", "#ff0000"},
			Color{"fuchsia", "#ff00ff"},
			Color{"yellow", "#ffff00"},
			Color{"white", "#ffffff"},
		},
	}
)

func main() {
	var code ColorCode
	fmt.Scanf("%s", &code)
	for {
		if code == "0" {
			break
		}
		name := colorTable.getNearestColor(code)
		fmt.Println(name)
		fmt.Scanf("%s", &code)
	}
}

func (colorstr ColorCode) parseColorValue() (float64, float64, float64) {
	rr, gg, bb := colorstr[1:3], colorstr[3:5], colorstr[5:7]
	rri, err1 := strconv.ParseUint(string(rr), 16, 8)
	ggi, err2 := strconv.ParseUint(string(gg), 16, 8)
	bbi, err3 := strconv.ParseUint(string(bb), 16, 8)
	if err1 != nil || err2 != nil || err3 != nil {
		err := fmt.Errorf(
			"Failed to read color strings, color code:%s, err: %v %v %v",
			colorstr, err1, err2, err3)
		panic(err)
	}
	return float64(rri), float64(ggi), float64(bbi)
}

func (table *ColorTable) getNearestColor(targetcode ColorCode) ColorName {
	var nearestColor ColorName
	var nearestValue = 1e5
	for _, v := range table.colors {
		trr, tgg, tbb := targetcode.parseColorValue()
		prr, pgg, pbb := v.code.parseColorValue()
		// diff := math.Sqrt(
		// 	math.Pow(prr-trr, 2) + math.Pow(pgg-tgg, 2) + math.Pow(pbb-tbb, 2))
		diff := math.Pow(prr-trr, 2) +
			math.Pow(pgg-tgg, 2) +
			math.Pow(pbb-tbb, 2)
		if nearestValue > diff {
			nearestValue = diff
			nearestColor = v.name
		}
	}
	return nearestColor
}

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

using namespace std;

int main(){

	string inp;
	string base = ("0123456789abcdef" );
	string scol[8] = { "black", "blue", "lime", "aqua", "red", "fuchsia", "yellow", "white" };
	int icol[8][3] = { { 0, 0, 0 }, { 0, 0, 256 }, { 0, 256, 0 }, { 0, 256, 256 }, { 256, 0, 0 }, { 256, 0, 256 }, { 256, 256, 0 }, { 256, 256, 256 } };
	int r, g, b;
	int ans;
	double ansnum;

	while (1){

		cin >> inp;
		if (inp == "0") break;

		r = base.find(inp[2]) * 1 + base.find(inp[1]) * 16;
		g = base.find(inp[4]) * 1 + base.find(inp[3]) * 16;
		b = base.find(inp[6]) * 1 + base.find(inp[5]) * 16;

		ans = 0;
		ansnum = sqrt(pow(r - icol[0][0], 2.0) + pow(g - icol[0][1], 2.0) + pow(b - icol[0][2], 2.0));
		for (int i = 1; i < 8; i++){
			if (ansnum>sqrt(pow(r - icol[i][0], 2.0) + pow(g - icol[i][1], 2.0) + pow(b - icol[i][2], 2.0))){
				ans = i;
				ansnum = sqrt(pow(r - icol[i][0], 2.0) + pow(g - icol[i][1], 2.0) + pow(b - icol[i][2], 2.0));
			}
		}

		cout << scol[ans] << endl;

	}
}

C++: #include <stdio.h>
#include <stack>
#include <math.h>

using namespace std;

int translate(char ch){
	if(ch >= '0' && ch <= '9')return ch - '0';
	else{
		return 10 + ch - 'a';
	}
}

int main(){

	char buf[10];
	int red,green,blue,diff[8],min,min_index;

	while(true){
		scanf("%s",buf);
		if(buf[0] == '0')break;

		red = 16*translate(buf[1])+translate(buf[2]);
		green = 16*translate(buf[3])+translate(buf[4]);
		blue = 16*translate(buf[5])+translate(buf[6]);

		diff[0] = red*red + green*green + blue*blue; //black
		diff[1] = red*red + green*green + (blue-255)*(blue-255); //blue
		diff[2] = red*red + (green-255)*(green-255) + blue*blue; //lime
		diff[3] = red*red + (green-255)*(green-255) + (blue-255)*(blue-255); //aqua
		diff[4] = (red-255)*(red-255) + green*green + blue*blue; //red
		diff[5] = (red-255)*(red-255) + green*green +(blue-255)*(blue-255); //fuchsia
		diff[6] = (red-255)*(red-255) + (green-255)*(green-255) + blue*blue; //fuchsia
		diff[7] = (red-255)*(red-255) + (green-255)*(green-255) +(blue-255)*(blue-255); //white

		min = 2147483647;

		for(int i=7; i >= 0; i--){
			if(diff[i] <= min){
				min = diff[i];
				min_index = i;
			}
		}

		switch(min_index){
		case 0:printf("black\n");
				break;
		case 1:printf("blue\n");
				break;
		case 2:printf("lime\n");
				break;
		case 3:printf("aqua\n");
				break;
		case 4:printf("red\n");
				break;
		case 5:printf("fuchsia\n");
				break;
		case 6:printf("yellow\n");
				break;
		case 7:printf("white\n");
				break;
		}

	}
    return 0;
}

C++: #include<iostream>
#include<map>
#include<math.h>

using namespace std;

map<int, int> MR;
map<int, int> MG;
map<int, int> MB;

void make(){
  MR[0] = 0;
  MG[0] = 0;
  MB[0] = 0;
  MR[1] = 0;
  MG[1] = 0;
  MB[1] = 255;
  MR[2] = 0;
  MG[2] = 255;
  MB[2] = 0;
  MR[3] = 0;
  MG[3] = 255;
  MB[3] = 255;
  MR[4] = 255;
  MG[4] = 0;
  MB[4] = 0;
  MR[5] = 255;
  MG[5] = 0;
  MB[5] = 255;
  MR[6] = 255;
  MG[6] = 255;
  MB[6] = 0;
  MR[7] = 255;
  MG[7] = 255;
  MB[7] = 255;
}

int main(){

  make();

  char in[2];
  int status = 0;

  while(cin >> in[0]){
    if(in[0] == '0') break;

    int r, g, b;

    for(int i = 0; i < 3; i++){
      
      cin >> in[0] >> in[1];

      for(int j = 0; j <= 1; j++){
	if(in[j] == 'a') in[j] -= 39;
	if(in[j] == 'b') in[j] -= 39;
	if(in[j] == 'c') in[j] -= 39;
	if(in[j] == 'd') in[j] -= 39;
	if(in[j] == 'e') in[j] -= 39;
	if(in[j] == 'f') in[j] -= 39;
      }

      if(i == 0) r = (in[0] - 48) * 16 + (in[1] - 48);
      if(i == 1) g = (in[0] - 48) * 16 + (in[1] - 48);
      if(i == 2) b = (in[0] - 48) * 16 + (in[1] - 48);
    }

    int d;
    int min, then;

    for(int j = 0; j < 8; j++){
      d = (r - MR[j])*(r - MR[j])+(g - MG[j])*(g - MG[j])+(b - MB[j])*(b - MB[j]);
      if(j == 0 || min > d){
	min = d;
	then = j;
      }
    }

    if(then == 0) cout << "black" <<endl;
    if(then == 1) cout << "blue" <<endl;
    if(then == 2) cout << "lime" <<endl;
    if(then == 3) cout << "aqua" <<endl;
    if(then == 4) cout << "red" <<endl;
    if(then == 5) cout << "fuchsia" <<endl;
    if(then == 6) cout << "yellow" <<endl;
    if(then == 7) cout << "white" <<endl;

  }
  return 0;
}

C++: #include <iostream> 
using namespace std;   int dir[5010];   void remove(){     int cnt = 0;     for(int i = 0 ; i < 5010 ; i++){         if( dir[i] == 31 ) dir[i] = 0,cnt++;     }     for(int k = 0 ; k <= cnt ; k++)     for(int i = 5009 ; i > 0 ; i--){         if( dir[i] && !dir[i-1] ){             swap(dir[i],dir[i-1]);         }     } }   void tate(int x,int l){     for(int i = 1 ; i <= l ; i++) dir[5010-i] |= (1<<x);           for(int _ = 0 ; _ < 10 ; _++)     for(int i = 5010-l+_ ; i > 0 ; i--){         if( (dir[i] >> x & 1) && (dir[i-1] >> x & 1) == 0 ){             dir[i] -= (1<<x);             dir[i-1] += (1<<x);         }else{             break;         }     }     remove(); }   void yoko(int x,int l){     int mask = ((1<<l)-1) << x;     dir[5009] = mask;     for(int i = 5009 ; i > 0 ; i--){         if( dir[i] && !(dir[i-1] & mask) ){             dir[i] -= mask;             dir[i-1] += mask;         }else{             break;         }     }     remove(); } int main(){     int n;     while(cin >> n && n){         for(int i = 0 ; i <= 5009 ; i++)             dir[i] = 0;                   for(int i = 0 ; i < n ; i++){             int d,l,x;             cin >> d >> l >> x;             x--;             if(d==1){                 yoko(x,l);             }else{                 tate(x,l);             }             int f = 0;             if( i == 10 ) continue;             for(    int j = 5009 ; j >= 0 ; j--){                 if(f||dir[j]){                                           f=true;                 }             }                  }         int ans = 0;         for(int i = 0 ; i < 5010 ; i++)             ans += __builtin_popcount(dir[i]);         cout << ans << endl;     } }