只加了先搜第一行第一列和最优性剪枝俩优化，1 ~ 5 正确，6 就 WA 掉了，求大佬帮忙看看 Orz

#include <vector>
#include <iomanip>
using namespace std;
const int S = 15;
typedef pair<int, int> P;
int n, a[S][S];
int ans[S][S], mns = 5050;
bool h[205], vis[105], ok = false;
int tot;
//vector<int> p;
vector<int> nxt[105];
vector<int> cab[10105];
void sieve() {
	h[1] = true; 
	for (int i = 2; i <= 200; i++) {
		if (!h[i]) {
//			p.push_back(i);
			for (int j = 2 * i; j <= 200; j += i) {
				h[j] = true;
			}	
		}
	}
} 
void dfs(int x, int y) {
	if (x == n + 1 && y == 2) {
		ok = true;/*
		for (int i = 1; i <= n; i++) {
			for (int j = 1; j <= n; j++) {
				cout << a[i][j] << ' ';
			}
			cout << endl;
		}*/
		mns = tot;
		for (int i = 1; i <= n; i++) {
			for (int j = 1; j <= n; j++) {
				ans[i][j] = a[i][j]; 
			}
		}
	}
	if (x == 1) { // the first line
		int pre = a[x][y - 1];
		for (auto i : nxt[pre]) {
			if (!vis[i]) {
				vis[i] = true;
				a[x][y] = i;
				tot += i;
				if (y == n) {
					dfs(2, 1);
				} else {
					dfs(x, y + 1);
				}
				vis[i] = false;
				a[x][y] = 0;
				tot -= i;
			}
		}
	} else if (y == 1) { // the first column
		int pre = a[x - 1][y];
		for (auto i : nxt[pre]) {
			if (!vis[i]) {
				vis[i] = true;
				a[x][y] = i;
				tot += i;
				if (x == n) {
					if (tot >= mns) {
						return;
					} else {
						dfs(2, 2);	
					}
				} else {
					dfs(x + 1, y);
				}
				vis[i] = false;
				tot -= i;
				a[x][y] = 0;
			}
		}
	} else {
		int lft = a[x - 1][y], up = a[x][y - 1];
		if (lft > up) {
			swap(up, lft);
		}
		int pre = lft * 100 + up;
		for (auto i : cab[pre]) {
			if (!vis[i]) {
				vis[i] = true;
				a[x][y] = i;
				if (y == n) {
					dfs(x + 1, 2);
				} else {
					dfs(x, y + 1);
				}
				vis[i] = false;
				a[x][y] = 0;
			} 
		}
	}
}
int main() {
	cin >> n;
	sieve();
	for (int i = 1; i <= n * n; i++) {
		for (int j = 1; j <= n * n; j++) {
			if (i != j) {
				if (!h[i + j]) {
					nxt[i].push_back(j);
				}
			}
		}
	}/*
	for (int i = 1; i <= n * n; i++) {
		cout << i << ": ";
		for (auto v : nxt[i]) {
			cout << v << ' ';
		}
		cout << endl;
	}*/
	bool ext1[105], ext2[105];
	for (int i = 1; i <= n * n; i++) {
		for (int j = i + 1; j <= n * n; j++) {
			for (int k = 1; k <= n * n; k++) {
				ext1[k] = false;
				ext2[k] = false;
			}
			for (auto v : nxt[i]) {
				ext1[v] = true;
			}
			for (auto v : nxt[j]) {
				ext2[v] = true;
			}
			int cob = i * 100 + j;
//			cout << cob << ": ";
			for (int k = 1; k <= n * n; k++) {
				if (ext1[k] && ext2[k]) {
					cab[cob].push_back(k);
//					cout << k << ' ';
				}
			}
//			cout << endl;
		}
	}
	a[1][1] = 1;
	vis[1] = true;
	dfs(1, 2);
	if (!ok) {
		cout << "NO";
		return 0;
	}
	cout << mns << endl;
	for (int i = 1; i <= n; i++) {
		for (int j = 1; j <= n; j++) {
			cout << ans[i][j] << ' ';
		}
		cout << endl;
	}
	return 0;
}