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<stdio.h>
#include<algorithm>
#include<queue>
using namespace std;
int dx[2][6]={{-1,-1,0,0,1,1},{-1,-1,0,0,1,1}};
int dy[2][6]={{-1,0,-1,1,-1,0},{1,0,-1,1,1,0}};
int bfs[110][110];
int m[110][110];
int main(){
	int a,b;
	while(scanf("%d%d",&b,&a),a){
		int c;scanf("%d",&c);
		queue<pair<int,int> >Q;
		for(int i=0;i<a;i++)for(int j=0;j<b;j++)bfs[i][j]=-1;
		for(int i=0;i<c;i++){
			int p,q;scanf("%d%d",&q,&p);
			p--;q--;
			bfs[p][q]=0;
			Q.push(make_pair(p,q));
		}
		while(Q.size()){
			int row=Q.front().first;
			int col=Q.front().second;
			Q.pop();
			int t=row%2;
			for(int i=0;i<6;i++){
				if(0<=row+dx[t][i]&&row+dx[t][i]<a&&0<=col+dy[t][i]&&col+dy[t][i]<b&&!~bfs[row+dx[t][i]][col+dy[t][i]]){
					bfs[row+dx[t][i]][col+dy[t][i]]=bfs[row][col]+1;
					Q.push(make_pair(row+dx[t][i],col+dy[t][i]));
				}
			}
		}
		int ret=0;
		int d;scanf("%d",&d);
		for(int i=0;i<d;i++){
			int p,q;scanf("%d%d",&q,&p);p--;q--;
			for(int j=0;j<a;j++)for(int k=0;k<b;k++)m[j][k]=-1;
			m[p][q]=0;
			Q.push(make_pair(p,q));
			while(Q.size()){
				int row=Q.front().first;
				int col=Q.front().second;
				Q.pop();
				int t=row%2;
				for(int j=0;j<6;j++){
					if(0<=row+dx[t][j]&&row+dx[t][j]<a&&0<=col+dy[t][j]&&col+dy[t][j]<b&&!~m[row+dx[t][j]][col+dy[t][j]]){
						m[row+dx[t][j]][col+dy[t][j]]=m[row][col]+1;
						Q.push(make_pair(row+dx[t][j],col+dy[t][j]));
					}
				}
			}
			int val=0;
			for(int j=0;j<a;j++)for(int k=0;k<b;k++)if(bfs[j][k]>m[j][k])val++;
			ret=max(val,ret);
		}
		printf("%d\n",ret);
	}
}

C++: #include <bits/stdc++.h>
using namespace std;
#define at(t, i) get<i>(t)
typedef pair<int, int> Pr;
typedef tuple<int, int, int> Tp;
const int INF = 1 << 28;
const int dx[] = {0, -1, -1, 0, 1, 1};
const int dy[][6] = {
	{-1, 0, 1, 1, 1, 0},
	{-1, -1, 0, 1, 0, -1},
};

int m, n;
int s, t;
Pr pos[11];
int dist[11][128][128];

int solve()
{
	fill_n(**dist, 11 * 128 * 128, INF);
	for (int i = 0; i <= s; i++){
		for (int j = 0; j <= 127; j++){
			for (int k = 0; k <= 127; k++){
				if (j == 0 || k == 0 || j == 127 || k == 127){
					dist[i][j][k] = 0;
				}
			}
		}
	}
	
	for (int i = 0; i <= s; i++){
		dist[i][pos[i].first][pos[i].second] = 0;
		queue<Tp> que;
		for (que.push(Tp(pos[i].first, pos[i].second, 0)); que.size(); que.pop()){
			Tp t = que.front();
			int x = at(t, 0);
			int y = at(t, 1);
			int d = at(t, 2);
			//printf("%d %d %d\n", x, y, d);
			if (dist[i][x][y] < d) continue;
			for (int dir = 0; dir < 6; dir++){
				int nx = x + dx[dir];
				int ny = y + dy[x & 1][dir];
				if (dist[i][nx][ny] > d + 1){
					dist[i][nx][ny] = d + 1;
					que.push(Tp(nx, ny, d + 1));
				}
			}
		}
	}
	
	/*for (int i = 0; i <= s; i++){
		for (int j = 1; j <= n; j++){
			for (int k = 1; k <= m; k++){
				printf("%d ", dist[i][j][k]);
			}
			puts("");
		}
		puts("\n");
	}*/
	
	int res = 0;
	for (int i = 1; i <= n; i++){
		for (int j = 1; j <= m; j++){
			int p = 0;
			for (int k = 1; k <= s; k++){
				if (dist[p][i][j] >= dist[k][i][j]){
					p = k;
				}
			}
			if (p == 0) res++;
		}
	}
	
	return res;
}

int main()
{
	while (scanf("%d %d", &m, &n), m){
		scanf("%d", &s);
		for (int i = 0; i < s; i++){
			int x, y;
			scanf("%d %d", &x, &y);
			pos[i + 1] = Pr(y, x);
		}
		
		int res = 0;
		scanf("%d", &t);
		for (int i = 0; i < t; i++){
			int p, q;
			scanf("%d %d", &p, &q);
			pos[0] = Pr(q, p);
			res = max(res, solve());
		}
		
		printf("%d\n", res);
	}
}