Language: C++

#define debug_interval ','
#define dump_interval ' '
#define debug_toggle 1

//{
#pragma GCC optimize ("O3","unroll-loops")
#pragma GCC target ("avx")
#include<bits/stdc++.h>
using namespace std;
#define hi cerr<<"hi"<<endl;
#define int long long
#define INT_MAX LLONG_MAX
#define rep(i,n) for(int i=0;i<(n);i++)
#define rep1(i,n) for(int i=1;i<=(n);i++)
#define pb push_back
#define all(v) (v).begin(),(v).end()
#define rall(v) (v).rbegin(),(v).rend()
#define fi first
#define se second
#define mp make_pair
#define rev reverse
#define dans dump(ans)
#define MOD 1000000007
#define amp(v,n) (v).count(n)?v[n]++:v[n]=1
#define sysp system("pause")
#define PI acos(-1)
#define ins insert
#define aer(v) (v).erase((v).begin(),(v).end()) 

//{
inline int toInt(string s){int v;istringstream sin(s);sin>>v;return v;}
template<class T> inline string toString(T x){ostringstream sout;sout<<x;return sout.str();}
template<class...A> inline void dump(){cout<<endl;}
template<class...A> inline void dump_rest() {cout<<endl;}
template<class T, class...A> inline void dump_rest(const T& first, const A&... rest){cout<<dump_interval<<first;dump_rest(rest...);}
template<class T,class...A> inline void dump(const T&first,const A&...rest){cout<<first;dump_rest(rest...);}
template<class...A> inline void debug(){cerr<<endl;}
template<class...A> inline void debug_rest() {cerr<<endl;}
template<class T, class...A> inline void debug_rest(const T& first, const A&... rest){cerr<<debug_interval<<first;debug_rest(rest...);}
template<class T,class...A> inline void debug(const T&first,const A&...rest){if(debug_toggle)cerr<<first,debug_rest(rest...);}
//}

typedef vector<int>vint;
typedef pair<int,int>pint;
typedef vector<pint>vpint;

template<typename A,typename B>inline void chmin(A &a,B b){if(a>b)a=b;}
template<typename A,typename B>inline void chmax(A &a,B b){if(a<b)a=b;}
template<int m>class mint{private:int i;public:mint() : i(0){}mint(int i): i((i%m+m)%m){}mint operator+(const mint& o){return o.i+i;}mint operator*(const mint& o){return o.i*i;}mint operator-(){return -i;}operator int() {return i;}};

//}

int h,w,n,px,py,dy[]={1,0,-1,0},dx[]={0,1,0,-1};
int f[111][111];
int d;

bool cango(int y,int x){
	return y>=0&&y<h&&x>=0&&x<w&&f[y][x]==0;
}

void walk(int cn,int v){
	if(v==0)return;
	f[py][px]=cn;
	/*bool test=cango(py+dy[d%4],px+dx[d%4]);
	cout<<test<<endl;
	rep(i,h+5){
		rep(j,w+5){
			cerr<<f[i][j];
		}
		cout<<endl;
	}
	cout<<endl;*/
	v--;
	if(cango(py+dy[d%4],px+dx[d%4])==0)d++;
	py+=dy[d%4];px+=dx[d%4];
	walk(cn,v);
}

main(){
	cin>>h>>w>>n;
	
	for(int c=1;c<n+1;c++){
		int a;
		cin>>a;
		walk(c,a);
		
	}
	rep(i,h){
		rep(j,w){
			cout<<f[i][j]<<(j+1==w?/n:' ');
		}
	}
}


Compiler output:
a.cc:12:9: warning: "INT_MAX" redefined
   12 | #define INT_MAX LLONG_MAX
      |         ^~~~~~~
In file included from /usr/include/c++/14/climits:42,
                 from /usr/include/x86_64-linux-gnu/c++/14/bits/stdc++.h:38,
                 from a.cc:8:
/usr/lib/gcc/x86_64-linux-gnu/14/include/limits.h:120:9: note: this is the location of the previous definition
  120 | #define INT_MAX __INT_MAX__
      |         ^~~~~~~
a.cc:79:1: warning: ISO C++ forbids declaration of 'main' with no type [-Wreturn-type]
   79 | main(){
      | ^~~~
a.cc: In function 'int main()':
a.cc:90:48: error: expected primary-expression before '/' token
   90 |                         cout<<f[i][j]<<(j+1==w?/n:' ');
      |                                                ^