Horse Pro
bfs搜索,但图中存在负值坐标,两种方法解决。
- 用数组标记,将原点设为300,300
- 用map标记
http://oj.jxust.edu.cn/contest/Problem?id=1689&pid=5
#include <iostream>
#include <cstdio>
#include <queue>
using namespace std;
typedef long long ll;
const int maxn = 100000 + 5;
int bx,by,e2,ey;
int vis[605][605];
int dir[8][2]={2,1,2,-1,-2,1,-2,-1,1,2,-1,2,1,-2,-1,-2};
struct Node
{
int x;
int y;
int len;
};
int bfs()
{
Node next;
next.x=bx;next.y=by;next.len=0;
queue<Node> q;
q.push(next);
while(!q.empty())
{
Node front;
front =q.front();
if(front.len>100) return -1;
q.pop();
for(int i=0;i<8;i++)
{
next.x=front.x+dir[i][0],next.y=front.y+dir[i][1],next.len=front.len+1;
if(vis[next.x][next.y]) continue;
if(next.x==e2&&next.y==ey) return next.len;
q.push(next);
vis[next.x][next.y]=1;
}
}
return -1;
}
int main() {
scanf("%d%d%d%d",&bx,&by,&e2,&ey);
e2=e2-bx+300;ey=ey-by+300;
bx=300;by=300;
int res=bfs();
printf("%d
",res);
return 0;
}
#include <iostream>
#include <cstdio>
#include <cstring>
#include <algorithm>
#include <cmath>
#include <queue>
#include <map>
using namespace std;
#define mem(a,b) memset(a,b,sizeof(a))
#define ll long long
const int maxn = 100100;
const int inf = 0x3f3f3f3f;
const int M = 1e9+7;
int to[8][2] = {2,1,2,-1,-2,1,-2,-1,1,2,-1,2,1,-2,-1,-2};
int a,b,c,d;
struct node
{
int x,y,z;
};
map<pair<int,int>, int> m;
int bfs()
{
node now,nex;
now.x = a,now.y= b,now.z = 0;
std::queue<node> q;
q.push(now);
while(!q.empty())
{
now = q.front();
q.pop();
if(now.x == c && now.y==d) return now.z;
if(now.z > 100) break;
for(int i = 0; i < 8; i++)
{
nex.x = now.x+to[i][0];
nex.y = now.y+to[i][1];
if(m[make_pair(nex.x,nex.y)]) continue;
m[make_pair(nex.x,nex.y)]=1;
nex.z = now.z+1;
q.push(nex);
}
}
return -1;
}
int main()
{
scanf("%d%d%d%d", &a,&b,&c,&d);
c=c-a;d=d-b;
a=0,b=0;
printf("%d
", bfs());
return 0;
}