尝试解决N皇后问题(持续优化)

0层：神圣打表(∞)

1 #include <cstdio>
2 int main() {
3     int arr[11] = {0,1,0,0,2,10,4,40,92,352,724};
4     int n;
5     while(~scanf("%d", &n) && n){
6         printf("%d\n", arr[n]);
7     }
8 }

1层：一维暴力回溯(13)

 1 const int maxn = 20;
 2 int G[maxn];    //G[c] = r
 3 int n, cnt;
 4
 5 bool ok(int cc) {
 6     for(int rr = 0; rr < cc; rr++) {
 7         if(G[rr] == G[cc] || abs(rr-cc) == abs(G[rr]-G[cc])) {
 8             return false;
 9         }
10     }
11     return true;
12 }
13
14 void dfs(int cc) {
15     if(cc == n) {
16         cnt++;
17         return ;
18     }
19     for(int rr = 0; rr < n; rr++) {
20         G[cc] = rr;
21         if(ok(cc)) {
22             dfs(cc + 1);
23         }
24     }
25 }