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  1. /*
  2. * @Author: hungeazy
  3. * @Date:   2026-03-08 09:02:54
  4. * @Last Modified by:   hungeazy
  5. * @Last Modified time: 2026-03-08 09:28:57
  6. */
  7. #include <bits/stdc++.h>
  8. #include <ext/pb_ds/assoc_container.hpp> 
  9. #include <ext/pb_ds/tree_policy.hpp> 
  10. // #pragma GCC optimize("O3")  
  11. // #pragma GCC optimize("unroll-loops")  
  12. // #pragma GCC target("avx2,bmi,bmi2,popcnt,lzcnt")  
  13. using namespace std;
  14. using namespace __gnu_pbds; 
  15. bool M1;
  16. #define fast ios_base::sync_with_stdio(false); cin.tie(NULL); cout.tie(NULL);
  17. // #define int long long 
  18. #define ll long long 
  19. #define ull unsigned long long
  20. #define sz(x) x.size()
  21. #define sqr(x) (1LL * (x) * (x))
  22. #define all(x) x.begin(), x.end()
  23. #define fill(f,x) memset(f,x,sizeof(f))
  24. #define FOR(i,l,r) for(int i=l;i<=r;i++)
  25. #define FOD(i,r,l) for(int i=r;i>=l;i--)
  26. #define debug(x) cout << #x << " = " << x << '\n'
  27. #define ii pair<int,int>
  28. #define iii pair<int,ii>
  29. #define di pair<ii,ii>
  30. #define vi vector<int>
  31. #define vii vector<ii>
  32. #define mii map<int,int>
  33. #define fi first
  34. #define se second
  35. #define pb push_back
  36. #define MOD 1000000007
  37. #define __lcm(a,b) (1ll * ((a) / __gcd((a), (b))) * (b))
  38. #define YES cout << "YES\n"
  39. #define NO cout << "NO\n"
  40. #define MASK(i) (1LL << (i))
  41. #define c_bit(i) __builtin_popcountll(i)
  42. #define BIT(x,i) ((x) & MASK(i))
  43. #define SET_ON(x,i) ((x) | MASK(i))
  44. #define SET_OFF(x,i) ((x) & ~MASK(i))
  45. #define oo 1e18
  46. #define name "BVGNT"
  47. #define endl '\n'
  48. #define memory() cerr << abs(&M2-&M1)/1024.0/1024 << " MB" << endl
  49. #define time() cerr << endl << "-------------Time:" << 1000.0 * clock() / CLOCKS_PER_SEC << "ms." << endl
  50. template<typename T> bool maximize(T &res, const T &val) { if (res < val){ res = val; return true; }; return false; }
  51. template<typename T> bool minimize(T &res, const T &val) { if (res > val){ res = val; return true; }; return false; }
  52. template <class T> using ordered_set = tree <T, null_type, less_equal <T>, rb_tree_tag,tree_order_statistics_node_update>;
  53. const int N = (int)1e6+10;
  54. vector<vi> a;
  55. int n,m;
  56. bool isPrime[N];
  57.  
  58. void sang()
  59. {
  60. 	fill(isPrime,true);
  61. 	isPrime[0] = isPrime[1] = false;
  62. 	FOR(i,2,sqrt(N-10))
  63. 		if (isPrime[i])
  64. 			for (int j = sqr(i); j <= N-10; j += i)
  65. 				isPrime[j] = false;
  66. }
  67.  
  68. namespace sub2 {
  69.  
  70. 	bool approved() {
  71. 		return n <= 50;
  72. 	}
  73.  
  74. 	void solve(void)
  75. 	{
  76. 		int ans = 0;
  77. 		bool check = false;
  78. 		FOD(len,min(n,m),1)
  79. 		{
  80. 			FOR(i,1,n-len+1)
  81. 			{
  82. 				FOR(j,1,m-len+1)
  83. 				{
  84. 					int cnt = 0;
  85. 					FOR(u,i,i+len-1)
  86. 						FOR(v,j,j+len-1)
  87. 						{
  88. 							cnt += !isPrime[a[u][v]];
  89. 							if (cnt > 1) goto li;
  90. 						}
  91. 					ans = sqr(len);
  92. 					check = true;
  93. 					break;
  94. 					li:;
  95. 				}
  96. 				if (check) break;
  97. 			}
  98. 			if (check) break;
  99. 		}
  100. 		cout << ans;
  101. 	}
  102.  
  103. }
  104.  
  105. namespace sub4 {
  106.  
  107. 	vector<vi> pre;
  108. 	vector<vector<bool>> bad;
  109.  
  110. 	int get(int u, int v, int x, int y) {
  111. 		return pre[x][y]-pre[u-1][y]-pre[x][v-1]+pre[u-1][v-1];
  112. 	}
  113.  
  114. 	void solve(void)
  115. 	{
  116.  		pre.resize(n+1,vi(m+1));
  117.  		bad.resize(n+1,vector<bool>(m+1));
  118.  		FOR(i,1,n)
  119.  			FOR(j,1,m)
  120.  				bad[i][j] = !isPrime[a[i][j]];
  121.  		FOR(i,1,n)
  122.  			FOR(j,1,m)
  123.  				pre[i][j] = pre[i-1][j]+pre[i][j-1]-pre[i-1][j-1]+bad[i][j];
  124.  		int ans = 0;
  125.  		bool ok = false;
  126.  		FOD(len,min(n,m),1)
  127.  		{
  128.  			FOR(i,1,n-len+1)
  129.  			{
  130.  				FOR(j,1,m-len+1)
  131.  				{
  132.  					int u = i+len-1, v = j+len-1;
  133.  					int sum = get(i,j,u,v);
  134.  					if (sum <= 1)
  135.  					{
  136.  						ans = sqr(len);
  137.  						ok = true;
  138.  						break;
  139.  					}
  140.  				}
  141.  				if (ok) break;
  142.  			}
  143.  			if (ok) break;
  144.  		}
  145.  		cout << ans;
  146. 	}
  147.  
  148. }
  149.  
  150. bool M2;
  151. signed main()
  152. {
  153.     fast;
  154.     if (fopen(name".inp","r"))
  155.     {
  156.     	freopen(name".inp","r",stdin);
  157.     	freopen(name".out","w",stdout);
  158.     }
  159.     sang();
  160.     cin >> n >> m;
  161.     a.resize(n+1,vi(m+1));
  162.     FOR(i,1,n)
  163.     	FOR(j,1,m) cin >> a[i][j];
  164.     if (sub2::approved()) return sub2::solve(), time(), memory(), 0;
  165.     sub4::solve();
  166.     time();
  167.     memory();
  168.     return 0;
  169. }
  170. // ██░ ██  █    ██  ███▄    █   ▄████
  171. //▓██░ ██▒ ██  ▓██▒ ██ ▀█   █  ██▒ ▀█▒
  172. //▒██▀▀██░▓██  ▒██░▓██  ▀█ ██▒▒██░▄▄▄░
  173. //░▓█ ░██ ▓▓█  ░██░▓██▒  ▐▌██▒░▓█  ██▓
  174. //░▓█▒░██▓▒▒█████▓ ▒██░   ▓██░░▒▓███▀▒
  175. // ▒ ░░▒░▒░▒▓▒ ▒ ▒ ░ ▒░   ▒ ▒  ░▒   ▒
  176. // ▒ ░▒░ ░░░▒░ ░ ░ ░ ░░   ░ ▒░  ░   ░
  177. // ░  ░░ ░ ░░░ ░ ░    ░   ░ ░ ░ ░   ░
  178. // ░  ░  ░   ░              ░       ░
Success #stdin #stdout #stderr 0.01s 5312KB
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-------------Time:8.722ms.
0.953819 MB
https://ideone.com/1LPD6c
language:
C++14 (gcc 8.3)
created:
3 hours ago
visibility:
public

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