Go: package main

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

var scanner = bufio.NewScanner(os.Stdin)

const INF = 0x7FFFFFFF

var (
	direction1 = [][]int{ // 奇数段目の移動方向
		{-1, 0}, {1, 0}, {0, -1}, {0, 1}, {1, -1}, {1, 1},
	}
	direction2 = [][]int{ // 偶数段目の移動方向
		{-1, -1}, {0, -1}, {1, 0}, {0, 1}, {-1, 1}, {-1, 0},
	}
)

func main() {
	for scanner.Scan() {
		buf := strings.Split(scanner.Text(), " ")
		m, _ := strconv.Atoi(buf[0])
		n, _ := strconv.Atoi(buf[1])
		if m == 0 && n == 0 {
			break
		}
		// initialize district_map
		/*
			district_map = [
				[-1, -1,  -1,  -1,  -1]
				[-1, INF, INF, INF, -1]
				[-1, INF, INF, INF, -1]
				[-1, INF, INF, INF, -1]
				[-1, INF, INF, INF, -1]
				[-1, -1,  -1,  -1,  -1]
			]
		*/
		district_map := make([][]int, n+2)
		for i := range district_map {
			district_map[i] = make([]int, m+2)
		}
		tmp1 := make([]int, m+2)
		for i := range tmp1 {
			tmp1[i] = -1
		}
		district_map[0] = tmp1
		district_map[n+1] = tmp1
		for i := 1; i < n+1; i++ {
			district_map[i] = make([]int, m+2)
			district_map[i][0] = -1
			district_map[i][m+1] = -1
			for j := 1; j < m+1; j++ {
				district_map[i][j] = INF
			}
		}

		scanner.Scan()
		s, _ := strconv.Atoi(scanner.Text())
		for i := 0; i < s; i++ {
			scanner.Scan()
			buf_ := strings.Split(scanner.Text(), " ")
			x, _ := strconv.Atoi(buf_[0])
			y, _ := strconv.Atoi(buf_[1])
			Search(Point{x, y}, district_map, m, n)
		}
		ans := 0
		scanner.Scan()
		t, _ := strconv.Atoi(scanner.Text())
		for i := 0; i < t; i++ {
			scanner.Scan()
			buf__ := strings.Split(scanner.Text(), " ")
			x, _ := strconv.Atoi(buf__[0])
			y, _ := strconv.Atoi(buf__[1])
			z := Count(Point{x, y}, district_map, m, n)
			ans = max(ans, z)
		}
		fmt.Println(ans)
	}
}

func max(a, b int) int {
	if a < b {
		return b
	}
	return a
}

type Point struct {
	x, y int
}

type Entry struct {
	hop   int
	point Point
}

func Search(p Point, mp [][]int, m, n int) {
	que := make([]Entry, 0)
	que = append(que, Entry{0, p})
	check := make([][]bool, n+2)
	for i := range check {
		check[i] = make([]bool, m+2)
	}
	check[p.y][p.x] = true
	mp[p.y][p.x] = 0
	var direction [][]int
	for len(que) > 0 {
		tmp := que[0]
		que = que[1:]
		dist, point := tmp.hop, tmp.point
		if point.y%2 == 0 {
			direction = direction1
		} else {
			direction = direction2
		}
		for _, d := range direction {
			nx, ny := point.x+d[0], point.y+d[1]
			if !check[ny][nx] && mp[ny][nx] != -1 {
				check[ny][nx] = true
				if mp[ny][nx] > dist+1 {
					mp[ny][nx] = dist + 1
				}
				que = append(que, Entry{dist + 1, Point{nx, ny}})
			}
		}
	}
}

func Count(p Point, mp [][]int, m, n int) int {
	que := make([]Entry, 0)
	que = append(que, Entry{0, p})
	check := make([][]bool, n+2)
	for i := range check {
		check[i] = make([]bool, m+2)
	}
	check[p.y][p.x] = true
	ans := 1
	var direction [][]int
	for len(que) > 0 {
		tmp := que[0]
		que = que[1:]
		dist, point := tmp.hop, tmp.point
		if point.y%2 == 0 {
			direction = direction1
		} else {
			direction = direction2
		}
		for _, d := range direction {
			nx, ny := point.x+d[0], point.y+d[1]
			if !check[ny][nx] && mp[ny][nx] != -1 {
				check[ny][nx] = true
				if mp[ny][nx] > dist+1 {
					ans++
				}
				que = append(que, Entry{dist + 1, Point{nx, ny}})
			}
		}
	}
	return ans
}

C++: #include<cstdio>
#include<algorithm>
#include<queue>

using namespace std;

int dx[2][6] = { {-1, 0, 1,-1,-1,0 } , {-1,0,0,1,1,1} };
int dy[2][6] = { { 0, 1, 0, 1,-1,-1} , {0,1,-1,0,1,-1} };

class P{
        public:
        int x;
        int y;
        int cost;
        P(){}
        P(int x,int y,int cost):x(x),y(y),cost(cost){}
};

int m,n,s;
int field[128][128];
int cp[128][128];
int res;

void bfs(int x,int y,int index){
        bool vis[128][128]={{0}};
        queue< P > Q;
        Q.push(P(x,y,1));
        field[x][y] = 1;
        res = 0;
        while( Q.size() ){
                P p = Q.front();Q.pop();
                for(int i = 0; i < 6; i++){
                        int nx = p.x+dx[p.y%2][i];
                        int ny = p.y+dy[p.y%2][i];
                        if(vis[p.x][p.y]++)continue;
                        if(nx < 0 || nx > m-1 || ny < 0 || ny > n-1)continue;
                        if(field[nx][ny] > p.cost+1){
                                field[nx][ny] = p.cost+1;
                                if(index == s+1){
                                        res++;
                                }
                                Q.push(P(nx,ny,p.cost+1));
                        }
                        else if(field[nx][ny] == p.cost+1){
                                field[nx][ny] = -1;
                        }
                }
        }
        return ;
}
void init(){
        for(int i = 0; i < m; i++){
                for(int j = 0; j < n; j++){
                        cp[i][j] = field[i][j];
                }
        }
}

void copy(){
        for(int i = 0; i < m; i++){
                for(int j = 0; j < n; j++){
                        field[i][j] = cp[i][j];
                }
        }
}

void output(){
        for(int i = 0; i < m; i++){
                for(int j = 0; j < n; j++){
                        printf("%3d",field[i][j]);
                }
                puts("");
        }
        return ;
}
int main(){
        while(scanf("%d",&m),m){

                scanf("%d",&n);
                scanf("%d",&s);

                for(int i = 0; i < 120; i++){
                        for(int j = 0; j < 120; j++){
                                field[i][j] = 99;
                        }
                }

                for(int i = 0; i < s; i++){
                        int x,y;
                        scanf("%d%d",&x,&y);
                        x--;y--;
                        //output();
                        bfs(x,y,i+1);
                }
                int t;
                scanf("%d",&t);
                init();
                int ans = -10000;
                for(int i = 0; i < t; i++){
                        int x,y;
                        scanf("%d%d",&x,&y);
                        x--;y--;
                        bfs(x,y,s+1);
                        //output();
                        ans = max(res,ans);
                        copy();
                }
                printf("%d\n",ans);
        }
        return 0;
}

C++: #include <algorithm>
#include <cctype>
#include <climits>
#include <cmath>
#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <functional>
#include <map>
#include <numeric>
#include <queue>
#include <set>
#include <vector>

using namespace std;

#define reps(i,f,n) for(int i=f; i<int(n); ++i)
#define rep(i,n) reps(i,0,n)

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

const int INF = 1001001001;

int dist(pii a, pii b)
{
	int dy = a.first - b.first;
	int dx = a.second - b.second;
	if(0 <= dy*dx){
		dy = abs(dy);
		dx = abs(dx);
		return dy + max(0, dx - (dy+1-min(a.first,b.first)%2)/2);
	}
	else{
		dy = abs(dy);
		dx = abs(dx);
		return dy + max(0, dx - (dy + min(a.first, b.first)%2)/2);
	}
}

int main()
{
	int m, n;
	while(scanf("%d%d", &m, &n), m){
		int s;
		scanf("%d", &s);
		pii conv[10];
		rep(i, s)
			scanf("%d%d", &conv[i].second, &conv[i].first);
		
		int d[101][101];
		rep(i, n) rep(j, m){
			d[i+1][j+1] = INF;
			rep(k, s)
				d[i+1][j+1] = min(d[i+1][j+1], dist(pii(i+1, j+1), conv[k]));
		}
		
		int t, ans = 0;
		scanf("%d", &t);
		rep(i, t){
			int x, y;
			scanf("%d%d", &x, &y);
			
			int cnt = 0;
			rep(j, n) rep(k, m)
				cnt += dist(pii(j, k), pii(y, x)) < d[j+1][k+1];
			ans = max(ans, cnt);
		}
		printf("%d\n", ans);
	}
	return 0;
}