joj2410: The knight problem

#include<iostream>   
#include<cstdio>   
#include<queue>   
using namespace std;  
typedef struct Point  
{  
    int x, y;  
}POINT;  
queue <POINT> me;  
POINT Begin , End;  
bool visited[9][9];  
bool flag;  
int ans;  
int movei[8]= {2,-2,1,-1,2,-2,1,-1};  
int movej[8]= {1,-1,2,-2,-1,1,-2,2};  
void init()  
{  
    int i, j;  
    for(i = 0; i < 9; i++)  
        for(j = 0; j < 9; j++)  
            visited[i][j] = false;  
}  
bool isok(POINT *p)  
{  
    if(p->x == End.x && p->y == End.y)  
        return true;  
    else  
        return false;  
}  
bool isin(POINT *pt)  
{  
    if(pt->x >= 1 && pt->x <= 8)  
        if(pt->y >= 1 && pt->y <= 8)  
            return true;  
    return false;  
}  
void change(char *str, POINT *pt)  
{  
    pt->x = str[0] - 'a' +1;  
    pt->y =str[1] - '0';  
}  
void bfs()  
{  
    int i, q, casenum;  
    POINT pt, tp;  
    casenum = 1;  
    while(!me.empty())  
    {  
        ans++;  
        q = 0;  
        while(casenum--)  
        {  
            pt = me.front();  
            me.pop();  
            for( i = 0; i < 8; i++)  
            {  
                tp.x = pt.x + movei[i];  
                tp.y = pt.y + movej[i];  
                if(isin(&tp))  
                {  
                    if(visited[tp.x][tp.y])  
                        continue;  
                    else  
                    {  
                        if(isok(&tp))  
                        {  
                            flag = true;  
                            return;  
                        }  
                        else  
                        {  
                            visited[tp.x][tp.y] = true;  
                            me.push(tp);  
                            q++;  
                        }  
                    }  
                }  
            }  
        }  
        casenum = q;  
    }  
    if(me.empty())  
        flag = false;  
    return ;  
}  
int main()  
{  
    int n, i, casenum;  
    POINT tp;  
    char str[10];  
    casenum = 1;  
    while(true)  
    {  
        while(!me.empty())  
        me.pop();  
        flag = true;  
        ans = 0;  
        init();  
        scanf("%d", &n);  
        if(-1 == n)  
            break;  
        for(i = 0; i < n; i++)  
        {  
            scanf("%s", str);  
            change(str, &tp);  
            visited[tp.x][tp.y] = true;  
        }  
        scanf("%s", str);  
        change(str, &Begin);  
        scanf("%s", str);  
        change(str, &End);  
        me.push(Begin);  
        visited[Begin.x][Begin.y] = true;  
        if(isok(&Begin))  
            printf("Board %d: %d moves\n", casenum, ans);  
        bfs();  
        if(flag)  
            printf("Board %d: %d moves\n", casenum, ans);  
        else  
            printf("Board %d: not reachable\n", casenum);  
        casenum++;  
    }  
    return 0;  
}