【小米oj】 小米兔的轨迹

刘汝佳紫书上都有

#define mm(a) memset(a,0,sizeof(a));
#define max(x,y) (x)>(y)?(x):(y)
#define min(x,y) (x)<(y)?(x):(y)
#define Fopen freopen("1.in","r",stdin); freopen("m.out","w",stdout);
#define rep(i,a,b) for(ll i=(a);i<=(b);i++)
#define per(i,b,a) for(ll i=(b);i>=(a);i--)
#include<bits/stdc++.h>
typedef long long ll;
#define PII pair<ll,ll>
using namespace std;
const int INF=0x3f3f3f3f;
const int MAXN=(int)2e5+5;
const int dx[]= {0,1,0,-1};
const int dy[]= {1,0,-1,0};
int n,m,a[1005][1005],vis[1005][1005];
vector<int>ans;
int main() {
    scanf("%d%d",&n,&m);
    for(int i=1; i<=n; i++)for(int j=1; j<=m; j++)scanf("%d",&a[i][j]);
    pair<int,int>now= {1,1};
    ans.push_back(a[1][1]);
    vis[1][1]=1;
    while(ans.size()!=n*m) {
        while(now.second<m&&!vis[now.first][now.second+1]) {
            now.second++;
            vis[now.first][now.second]=1;
            ans.push_back(a[now.first][now.second]);
        }
        while(now.first<n&&!vis[now.first+1][now.second]) {
            now.first++;
            vis[now.first][now.second]=1;
            ans.push_back(a[now.first][now.second]);
        }
        while(now.second>1&&!vis[now.first][now.second-1]) {
            now.second--;
            vis[now.first][now.second]=1;
            ans.push_back(a[now.first][now.second]);
        }
        while(now.first>1&&!vis[now.first-1][now.second]) {
            now.first--;
            vis[now.first][now.second]=1;
            ans.push_back(a[now.first][now.second]);
        }
    }
    for(auto i:ans)printf("%d ",i);
    printf("
");
    return 0;
}