1.离开中山路

 

#include<iostream>
#include<cstring>
#include<queue>
#include<algorithm>
#include<string>
using namespace std;
int x1,x2,y1,y2;
int n,n1,m1;
const int N=1010;typedef pair<int,int> PII;
queue<PII> q;int dist[N][N];
char g[N][N];int dx[]={-1,0,1,0};
int dy[]={0,1,0,-1};int bfs(int x1,int y1)
{memset(dist,-1,sizeof dist);q.push({x1,y1});//注意格式 dist[x1][y1]=0;while(!q.empty()){PII t=q.front();q.pop();for(int i=0;i<4;i++){n1=dx[i]+t.first;m1=dy[i]+t.second;if(n1<1||n1>n||m1<1||m1>n) continue;if(g[n1][m1]=='1') continue;if(dist[n1][m1]>0) continue;q.push({n1,m1});dist[n1][m1]=dist[t.first][t.second]+1;// ***if(n1==x2&&m1==y2){return dist[x2][y2];}}}return dist[x2][y2];
}int main()
{scanf("%d",&n);for(int i=1;i<=n;i++){for(int j=1;j<=n;j++){cin>>g[i][j];//scanf("%c",&g[i][j]);}}scanf("%d %d %d %d",&x1,&y1,&x2,&y2);int res=bfs(x1,y1);cout<<res;return 0;} 

2.马的遍历

 

//马的遍历
#include<iostream>
#include<algorithm>
#include<cstring>
using namespace std;
/*如何用数组模拟队列：省时间 
对头hh,队尾tt 实现队列的插入操作：q[tt++]=x；x是要插入的数字实现队列的弹出操作：hh++；如何给队列判空：当hh++<=tt int hh=0,tt=0;*/typedef pair<int,int> PII;const int N=410;int n,m;int dist[N][N];PII q[N*N];int dx[]={2,2,1,1,-1,-1,-2,-2};int dy[]={-1,1,2,-2,2,-2,1,-1};void bfs(int x1,int y1){memset(dist,-1,sizeof dist);q[0]={x1,y1};dist[x1][y1]=0;int hh=0,tt=0;while(hh<=tt){PII t=q[hh++];//t=q.front,why++?//hh++;//pop//t=q[hh++];for(int i=0;i<8;i++){int a=t.first+dx[i];int b=t.second+dy[i];if(a<1||a>n||b<1||b>m) continue;if(dist[a][b]>=0) continue;dist[a][b]=dist[t.first][t.second]+1;q[++tt]={a,b};//}}}int main()
{int x1,y1;scanf("%d %d %d %d",&n,&m,&x1,&y1);bfs(x1,y1);for(int i=1;i<=n;i++){for(int j=1;j<=m;j++){printf("%-5d",dist[i][j]);//%-5d左补空格，右对齐 }cout<<endl;	}return 0;
}