POJ 2243 Knight Moves

http://poj.org/problem?id=2243

BFS模板题

#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <queue>
using namespace std;
char pos_start[3],pos_end[3];
bool visited[20][20]={false};
int dis[20][20]={0};
typedef struct Node {
    int x,y;
}Node;
Node nodes[8]={{-1,-2},{-2,-1},{-2,1},{-1,2},{1,-2},{1,2},{2,-1},{2,1}};
void init()
{
    memset(visited,false,sizeof(visited));
    int i,j;
    for(i=0;i<20;i++) 
        for(j=0;j<20;j++)
            dis[i][j]=0;
}
bool check(int x,int y)
{
    if(!(1<=x&&x<=8&&0<=y&&y<=7))    return false;
    return true;
}
int bfs(int s_x,int s_y,int e_x,int e_y)
{
    queue<int> Q;
    Q.push(s_x);
    Q.push(s_y);
    dis[s_x][s_y]=0;
    while(!Q.empty()) {
        int x=Q.front();
        Q.pop();
        int y=Q.front();
        Q.pop();
        if(x==e_x&&y==e_y)    return dis[x][y];
        visited[x][y]=true;
        int i;
        for(i=0;i<8;i++) {
            if(check(x+nodes[i].x,y+nodes[i].y)&&!visited[x+nodes[i].x][y+nodes[i].y]) {
                Q.push(x+nodes[i].x);
                Q.push(y+nodes[i].y);
                dis[x+nodes[i].x][y+nodes[i].y]=dis[x][y]+1;
            }
        }
    }        
}

int main()
{
    while(scanf("%s%s",pos_start,pos_end)!=EOF) {
        int start_x=pos_start[1]-'0';
        int start_y=pos_start[0]-'a';
        int end_x=pos_end[1]-'0';
        int end_y=pos_end[0]-'a';
        int moves=bfs(start_x,start_y,end_x,end_y);
        init();
        printf("To get from %s to %s takes %d knight moves.\n",pos_start,pos_end,moves);
    }
    return 0;
}