迷宫问题
844.走迷宫
手写队列
#include <iostream>
#include <cstdio>
#include <cstring>
#include <algorithm>
#include <queue>
using namespace std;
const int N = 110;
#define x first
#define y second
int g[N][N];
int d[N][N];
typedef pair<int,int>PII;
int n,m;
PII q[N*N];
int bfs()
{
memset(d,-1,sizeof d);
d[0][0]=0;
q[0]={0,0};
int hh=0,tt=0;
int dx[4]={-1,0,1,0},dy[4]={0,1,0,-1};
while (hh<=tt)
{
PII t=q[hh++];
for (int i=0;i<4;i++)
{
int x = t.x+dx[i];
int y = t.y+dy[i];
if (x<0||x>=n||y<0||y>=m) continue;
if (d[x][y]!=-1) continue;
if (g[x][y]==1) continue;
d[x][y]=d[t.x][t.y]+1;
q[++tt]={x,y};
}
}
return d[n-1][m-1];
}
int main()
{
cin>>n>>m;
for (int i=0;i<n;i++)
for (int j=0;j<m;j++)
cin>>g[i][j];
cout<<bfs()<<endl;
return 0;
}
直接用STL的queue,更方便感觉
#include <iostream>
#include <cstdio>
#include <cstring>
#include <algorithm>
#include <queue>
#define x first
#define y second
using namespace std;
const int N =110;
int g[N][N];
int d[N][N];
typedef pair<int,int>PII;
int n,m;
int bfs()
{
queue<PII> q;
memset(d,-1,sizeof d);
q.push({0,0});
d[0][0]=0;
int dx[4]={-1,0,1,0},dy[4]={0,1,0,-1};
while (q.size())
{
PII t=q.front();
q.pop();
for (int i=0;i<4;i++)
{
int x=t.x+dx[i];
int y=t.y+dy[i];
if (x<0||x>=n||y<0||y>=m) continue;
if (g[x][y]==1) continue;
if (d[x][y]!=-1) continue;
d[x][y]=d[t.x][t.y]+1;
q.push({x,y});
}
}
return d[n-1][m-1];
}
int main()
{
cin>>n>>m;
for (int i=0;i<n;i++)
for (int j=0;j<m;j++)
cin>>g[i][j];
cout<<bfs()<<endl;
return 0;
}
迷宫问题变形
1101.献给阿尔吉侬的花束
#include <iostream>
#include <cstdio>
#include <cstring>
#include <algorithm>
#include <queue>
using namespace std;
#define x first
#define y second
const int N = 210;
typedef pair<int,int>PII;
char g[N][N];
int d[N][N];
int n,m;
int T;
int bfs(PII start,PII end)
{
queue<PII>q;
memset(d,-1,sizeof d);
d[start.x][start.y]=0;
q.push(start);
int dx[4]={-1,0,1,-0},dy[4]={0,1,0,-1};
while (q.size())
{
PII t = q.front();
q.pop();
for (int i=0;i<4;i++)
{
int x=t.x+dx[i];
int y=t.y+dy[i];
if (x<0||x>=n||y<0||y>=m) continue;
if (d[x][y]!=-1) continue;
if (g[x][y]=='#') continue;
d[x][y]=d[t.x][t.y]+1;
if (end==make_pair(x,y)) return d[x][y];
q.push({x,y});
}
}
return -1;
}
int main()
{
scanf("%d",&T);
while (T--)
{
scanf("%d%d",&n,&m);
for (int i=0;i<n;i++) scanf("%s",g[i]);
PII start,end;
for (int i=0;i<n;i++)
{
for (int j=0;j<m;j++)
{
if (g[i][j]=='S')
{
start={i,j};
}
else if (g[i][j]=='E')
{
end={i,j};
}
}
}
int ans=bfs(start,end);
if (ans==-1) printf("oop!\n");
else printf("%d\n",ans);
}
return 0;
}
迷宫问题升级版
1233.全球变暖
#include <iostream>
#include <cstdio>
#include <cstring>
#include <algorithm>
#include <queue>
#define x first
#define y second
using namespace std;
const int N =110;
int g[N][N];
int d[N][N];
typedef pair<int,int>PII;
int n,m;
int bfs()
{
queue<PII> q;
memset(d,-1,sizeof d);
q.push({0,0});
d[0][0]=0;
int dx[4]={-1,0,1,0},dy[4]={0,1,0,-1};
while (q.size())
{
PII t=q.front();
q.pop();
for (int i=0;i<4;i++)
{
int x=t.x+dx[i];
int y=t.y+dy[i];
if (x<0||x>=n||y<0||y>=m) continue;
if (g[x][y]==1) continue;
if (d[x][y]!=-1) continue;
d[x][y]=d[t.x][t.y]+1;
q.push({x,y});
}
}
return d[n-1][m-1];
}
int main()
{
cin>>n>>m;
for (int i=0;i<n;i++)
for (int j=0;j<m;j++)
cin>>g[i][j];
cout<<bfs()<<endl;
return 0;
}
亲测手写队列比STL快近一倍!!!
迷宫问题的三维版本
地牢大师
bfs借助STL的queue
#include <iostream>
#include <cstdio>
#include <cstring>
#include <string>
#include <algorithm>
#include <queue>
using namespace std;
const int N = 110;
int d[N][N][N];
int l,r,c;
char g[N][N][N];
struct Point
{
int x,y,z;
};
int bfs(Point start,Point end)
{
queue<Point>q;
memset(d,-1,sizeof d);
d[start.x][start.y][start.z]=0;
q.push(start);
int dx[6]={1,-1,0,0,0,0},dy[6]={0,0,1,-1,0,0},dz[6]={0,0,0,0,1,-1};
while (q.size())
{
Point t=q.front();
q.pop();
for (int i=0;i<6;i++)
{
int x=t.x+dx[i];
int y=t.y+dy[i];
int z=t.z+dz[i];
if (x<0||x>=l||y<0||y>=r||z<0||z>=c) continue;
if (g[x][y][z]=='#') continue;
if (d[x][y][z]!=-1) continue;
d[x][y][z]=d[t.x][t.y][t.z]+1;
if (x==end.x&&y==end.y&&z==end.z) return d[x][y][z];
q.push({x,y,z});
}
}
return -1;
}
int main()
{
while (scanf("%d%d%d",&l,&r,&c),l||r||c)
{
Point start,end;
for (int i=0;i<l;i++)
{
for (int j=0;j<r;j++)
{
scanf("%s",g[i][j]);
for (int k=0;k<c;k++)
{
char x=g[i][j][k];
if (x=='S') start={i,j,k};
else if (x=='E') end={i,j,k};
}
}
}
int ans=bfs(start,end);
if (ans==-1) printf("Trapped!\n");
else printf("Escaped in %d minute(s).\n",ans);
}
return 0;
}
手写队列
#include <iostream>
#include <cstdio>
#include <cstring>
#include <string>
#include <algorithm>
using namespace std;
const int N = 110;
int d[N][N][N];
int l,r,c;
char g[N][N][N];
struct Point
{
int x,y,z;
};
Point q[N*N*N];
int bfs(Point start,Point end)
{
memset(d,-1,sizeof d);
d[start.x][start.y][start.z]=0;
int dx[6]={1,-1,0,0,0,0},dy[6]={0,0,1,-1,0,0},dz[6]={0,0,0,0,1,-1};
q[0]=start;
int hh=0,tt=0;
while (hh<=tt)
{
Point t=q[hh];
hh++;
for (int i=0;i<6;i++)
{
int x=t.x+dx[i];
int y=t.y+dy[i];
int z=t.z+dz[i];
if (x<0||x>=l||y<0||y>=r||z<0||z>=c) continue;
if (g[x][y][z]=='#') continue;
if (d[x][y][z]!=-1) continue;
d[x][y][z]=d[t.x][t.y][t.z]+1;
if (x==end.x&&y==end.y&&z==end.z) return d[x][y][z];
q[++tt]={x,y,z};
}
}
return -1;
}
int main()
{
while (scanf("%d%d%d",&l,&r,&c),l||r||c)
{
Point start,end;
for (int i=0;i<l;i++)
{
for (int j=0;j<r;j++)
{
scanf("%s",g[i][j]);
for (int k=0;k<c;k++)
{
char x=g[i][j][k];
if (x=='S') start={i,j,k};
else if (x=='E') end={i,j,k};
}
}
}
int ans=bfs(start,end);
if (ans==-1) printf("Trapped!\n");
else printf("Escaped in %d minute(s).\n",ans);
}
return 0;
}
八数码问题(字符串的更新)
八数码问题
#include <iostream>
#include <cstdio>
#include <cstring>
#include <string>
#include <algorithm>
#include <queue>
#include <unordered_map>
using namespace std;
int bfs(string s)
{
string end="12345678x";
queue<string>q;
unordered_map<string,int>d;
int dx[4]={-1,0,1,0},dy[4]={0,1,0,-1};
d[s]=0;
q.push(s);
while (q.size())
{
string t=q.front();
int dist=d[t];
q.pop();
int k=t.find('x');
int x=k/3,y=k%3;
for (int i=0;i<4;i++)
{
int a=x+dx[i];
int b=y+dy[i];
if (a>=0&&a<3&&b>=0&&b<3)
{
swap(t[k],t[a*3+b]);
if (!d.count(t))
{
d[t]=dist+1;
if (t==end) return d[t];
q.push(t);
}
swap(t[k],t[a*3+b]);
}
}
}
return -1;
}
int main()
{
string s;
for (int i=0;i<9;i++)
{
char c;
cin>>c;
s+=c;
}
cout<<bfs(s)<<endl;
return 0;
}
bfs经典
红与黑
#include <iostream>
#include <cstdio>
#include <algorithm>
#include <cstring>
#include <queue>
using namespace std;
typedef pair<int,int> PII;
#define x first
#define y second
const int N = 30;
char g[N][N];
int n,m;
int st[N][N];
void bfs(PII start,int &ans)
{
queue<PII>q;
q.push(start);
st[start.x][start.y]=1;
while (q.size())
{
PII t=q.front();
q.pop();
int dx[4]={-1,0,1,0},dy[4]={0,1,0,-1};
for (int i=0;i<4;i++)
{
int x=t.x+dx[i];
int y=t.y+dy[i];
if (g[x][y]=='#') continue;
if (st[x][y]!=-1) continue;
if (x<0||x>=n||y<0||y>=m) continue;
ans++;
st[x][y]=1;
q.push({x,y});
}
}
}
int main()
{
while (scanf("%d%d",&m,&n),m||n)
{
memset(st,-1,sizeof st);
int ans=1;
for (int i=0;i<n;i++) scanf("%s",g[i]);
PII start;
for (int i=0;i<n;i++)
for (int j=0;j<m;j++)
{
if (g[i][j]=='@')
{
start={i,j};
}
}
bfs(start,ans);
printf("%d\n",ans);
}
return 0;
}