补基础题（BFS）

P1135 奇怪的电梯 - 洛谷 | 计算机科学教育新生态 (luogu.com.cn)

#include<iostream> 
#include<queue>
#include<cstring>
using namespace std;
const int N=210;
int K[N],n,A,B,vis[N];
struct node{
    int now,step;
};
#define check(a) (a>=1&&a<=n)
void BFS(){
    node begin,next;
    begin.now=A;
    begin.step=0;
    vis[begin.now]=1;
    queue<node> q;
    q.push(begin);
    while(!q.empty()){
        begin=q.front();
        q.pop();
        if(begin.now==B){
            cout<<begin.step<<endl;
            return ;
        }
        int c;
        c=begin.now+K[begin.now];
        if(check(c)&&!vis[c]){
            vis[c]=1;
            next.now=c;
            next.step=begin.step+1;
            q.push(next);
        }
        c=begin.now-K[begin.now];
        if(check(c)&&!vis[c]){
            vis[c]=1;
            next.now=c;
            next.step=begin.step+1;
            q.push(next);
        }
    }
    cout<<"-1"<<endl;
}
signed main(){
    ios::sync_with_stdio(false);
    cin.tie(0);cout.tie(0);
    cin>>n>>A>>B;
    for(int i=1;i<=n;i++) cin>>K[i];
    memset(vis,0,sizeof(vis));
    BFS();
    
    return 0;
}

P1443 马的遍历 - 洛谷 | 计算机科学教育新生态 (luogu.com.cn)

#include<iostream> 
#include<queue>
#include<cstring>
using namespace std;
const int INF=0x3f3f3f3f;
const int N=410;
int n,m,x,y,vis[N][N],s[N][N];
struct node{
    int dx,dy,step;
};
#define check(a,b) (a>=1&&a<=n&&b>=1&&b<=m)
void BFS(){
    node begin,next;
    begin.dx=x;
    begin.dy=y;
    begin.step=0;
    vis[begin.dx][begin.dy]=-INF;
    queue<node> q;
    q.push(begin);
    while(!q.empty()){
        begin=q.front();
        q.pop();
        int nx,ny;
        nx=begin.dx-1;
        ny=begin.dy+2;
        if(check(nx,ny)&&!vis[nx][ny]){
            next.dx=nx;
            next.dy=ny;
            next.step=begin.step+1;
            vis[nx][ny]=next.step;
            q.push(next);
        }
        nx=begin.dx-1;
        ny=begin.dy-2;
        if(check(nx,ny)&&!vis[nx][ny]){
            next.dx=nx;
            next.dy=ny;
            next.step=begin.step+1;
            vis[nx][ny]=next.step;
            q.push(next);
        }
        nx=begin.dx-2;
        ny=begin.dy+1;
        if(check(nx,ny)&&!vis[nx][ny]){
            next.dx=nx;
            next.dy=ny;
            next.step=begin.step+1;
            vis[nx][ny]=next.step;
            q.push(next);
        }
        nx=begin.dx-2;
        ny=begin.dy-1;
        if(check(nx,ny)&&!vis[nx][ny]){
            next.dx=nx;
            next.dy=ny;
            next.step=begin.step+1;
            vis[nx][ny]=next.step;
            q.push(next);
        }
        nx=begin.dx+1;
        ny=begin.dy+2;
        if(check(nx,ny)&&!vis[nx][ny]){
            next.dx=nx;
            next.dy=ny;
            next.step=begin.step+1;
            vis[nx][ny]=next.step;
            q.push(next);
        }
        nx=begin.dx+1;
        ny=begin.dy-2;
        if(check(nx,ny)&&!vis[nx][ny]){
            next.dx=nx;
            next.dy=ny;
            next.step=begin.step+1;
            vis[nx][ny]=next.step;
            q.push(next);
        }
        nx=begin.dx+2;
        ny=begin.dy+1;
        if(check(nx,ny)&&!vis[nx][ny]){
            next.dx=nx;
            next.dy=ny;
            next.step=begin.step+1;
            vis[nx][ny]=next.step;
            q.push(next);
        }
        nx=begin.dx+2;
        ny=begin.dy-1;
        if(check(nx,ny)&&!vis[nx][ny]){
            next.dx=nx;
            next.dy=ny;
            next.step=begin.step+1;
            vis[nx][ny]=next.step;
            q.push(next);
        }
    }
    for(int i=1;i<=n;i++){
        for(int j=1;j<=m;j++){
            if(vis[i][j]==0){
                vis[i][j]=-1;
            }
        }
    }
    vis[x][y]=0;
}
signed main(){
    ios::sync_with_stdio(false);
    cin.tie(0);cout.tie(0);
    cin>>n>>m>>x>>y;
    memset(vis,0,sizeof(vis));
    BFS();
    for(int i=1;i<=n;i++){
        for(int j=1;j<=m;j++){
            cout<<vis[i][j]<<"    ";
        }
        cout<<endl;
    }
    return 0;
}

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