B15 BFS 抓住那头牛

zjy:

#include<bits/stdc++.h>
using namespace std;
const int N=1e5+10;
int ans[N],d[3]={1,-1,0};
int main(){
    int x,y;scanf("%d%d",&x,&y);
    
    if(x==y){
        printf("0\n");
        return 0;
    }
    
    deque<int>q;q.push_back(x);
    memset(ans,0,sizeof(ans));
    while(!q.empty()){
        int x=q.front();
        q.pop_front();d[2]=x;
        for(int i=0;i<3;i++){
            int xx=x+d[i];
            if(xx>=0&&xx<= 1e5 && !ans[xx] ){
                q.push_back(xx);
                ans[xx]=ans[x]+1;
                if(xx==y)break;
            }
        }
    }
    printf("%d\n",ans[y]);
    return 0;
}