刘汝佳紫书上都有
1 #define mm(a) memset(a,0,sizeof(a)); 2 #define max(x,y) (x)>(y)?(x):(y) 3 #define min(x,y) (x)<(y)?(x):(y) 4 #define Fopen freopen("1.in","r",stdin); freopen("m.out","w",stdout); 5 #define rep(i,a,b) for(ll i=(a);i<=(b);i++) 6 #define per(i,b,a) for(ll i=(b);i>=(a);i--) 7 #include<bits/stdc++.h> 8 typedef long long ll; 9 #define PII pair<ll,ll> 10 using namespace std; 11 const int INF=0x3f3f3f3f; 12 const int MAXN=(int)2e5+5; 13 const int dx[]= {0,1,0,-1}; 14 const int dy[]= {1,0,-1,0}; 15 int n,m,a[1005][1005],vis[1005][1005]; 16 vector<int>ans; 17 int main() { 18 scanf("%d%d",&n,&m); 19 for(int i=1; i<=n; i++)for(int j=1; j<=m; j++)scanf("%d",&a[i][j]); 20 pair<int,int>now= {1,1}; 21 ans.push_back(a[1][1]); 22 vis[1][1]=1; 23 while(ans.size()!=n*m) { 24 while(now.second<m&&!vis[now.first][now.second+1]) { 25 now.second++; 26 vis[now.first][now.second]=1; 27 ans.push_back(a[now.first][now.second]); 28 } 29 while(now.first<n&&!vis[now.first+1][now.second]) { 30 now.first++; 31 vis[now.first][now.second]=1; 32 ans.push_back(a[now.first][now.second]); 33 } 34 while(now.second>1&&!vis[now.first][now.second-1]) { 35 now.second--; 36 vis[now.first][now.second]=1; 37 ans.push_back(a[now.first][now.second]); 38 } 39 while(now.first>1&&!vis[now.first-1][now.second]) { 40 now.first--; 41 vis[now.first][now.second]=1; 42 ans.push_back(a[now.first][now.second]); 43 } 44 } 45 for(auto i:ans)printf("%d ",i); 46 printf(" "); 47 return 0; 48 }