uva 439

BFS稍微改变了一下，走的步法不一样了。
AC代码

#include <iostream>
#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <queue>
#include <vector>
using namespace std;

const int maxn = 10;
int vis[maxn][maxn];
int dis[maxn][maxn];
int x0,y0,x1,y1;
int dr[8][2] ={-2,1,-1,2,1,2,2,1,2,-1,1,-2,-1,-2,-2,-1};
int ans;

struct node{
    int x,y;
};

node p[maxn][maxn];

void print_road(node u);

void bfs(){
    node init,next;
    queue<node> q;
    init.x = x0;init.y = y0;
    q.push(init);
    dis[x0][y0] = 0;
    vis[x0][y0] = 1;
    while(!q.empty()){
        next = q.front();q.pop();
        if(next.x == x1 && next.y == y1) {ans = dis[next.x][next.y];return;}
        for(int i=0;i<8;i++){
            int dx = next.x + dr[i][0];
            int dy = next.y + dr[i][1];
            if(dx < 1 || dx > 8 || dy < 1 || dy > 8 || vis[dx][dy]) continue;
            init.x = dx; init.y = dy; q.push(init);
            vis[dx][dy] = 1;dis[dx][dy] = dis[next.x][next.y]+1;p[dx][dy] = next;
        }
    }
    ans = -1;
}


int main(){
    string s,t;
    while(cin>>s){
        memset(vis,0,sizeof(vis));
        memset(dis,0,sizeof(dis));
        cin >> t;
        y0 = s[0] - ‘a‘ + 1;
        x0 = s[1] - ‘0‘;
        y1 = t[0] - ‘a‘ + 1;
        x1 = t[1] - ‘0‘; 
        bfs();
        if(ans == -1) cout<<"No Solution!"<<endl;
        else 
        cout<<"To get from "<<s<<" to "<<t<<" takes "<<ans<<" knight moves."<<endl;
    }
    return 0;
}

作为练习，我还写了一个打印路程的函数。

#include <iostream>
#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <queue>
#include <vector>
using namespace std;

const int maxn = 10;
int vis[maxn][maxn];
int dis[maxn][maxn];
int x0,y0,x1,y1;
int dr[8][2] ={-2,1,-1,2,1,2,2,1,2,-1,1,-2,-1,-2,-2,-1};
int ans;

struct node{
    int x,y;
};

node p[maxn][maxn];

void print_road(node u);

void bfs(){
    node init,next;
    queue<node> q;
    init.x = x0;init.y = y0;
    q.push(init);
    dis[x0][y0] = 0;
    vis[x0][y0] = 1;
    while(!q.empty()){
        next = q.front();q.pop();
        if(next.x == x1 && next.y == y1) {ans = dis[next.x][next.y];print_road(next);return;}
        for(int i=0;i<8;i++){
            int dx = next.x + dr[i][0];
            int dy = next.y + dr[i][1];
            if(dx < 1 || dx > 8 || dy < 1 || dy > 8 || vis[dx][dy]) continue;
            init.x = dx; init.y = dy; q.push(init);
            vis[dx][dy] = 1;dis[dx][dy] = dis[next.x][next.y]+1;p[dx][dy] = next;
        }
    }
    ans = -1;
}

void print_road(node u){
    vector<node> v;
    for(;;){
        v.push_back(u);
        if(u.x == x0 && u.y == y0) break;
        u = p[u.x][u.y];
    }

    for(int i = v.size()-1;i>=0;i--){
        printf("(%d,%c)",v[i].x,‘a‘+v[i].y-1);
    }
    printf("\n");
}

int main(){
    int T;
    cin >> T;
    string s,t;
    while(T--){
        memset(vis,0,sizeof(vis));
        memset(dis,0,sizeof(dis));
        cin >> s >> t;
        y0 = s[0] - ‘a‘ + 1;
        x0 = s[1] - ‘0‘;
        y1 = t[0] - ‘a‘ + 1;
        x1 = t[1] - ‘0‘; 
        bfs();
        if(ans == -1) cout<<"No Solution!"<<endl;
        else cout<<ans<<endl;
    }
    return 0;
}