1 class Solution {
2 public:
3 void generateResults(vector<vector<string> > &rlts, int n, int index, int * cur, bool * flag1, bool * flag2, bool* flag3){
4 for (int i=0; i<n; i++){
5 int j = index+i;
6 int k = index-i+n-1;
7 if (flag1[i] || flag2[j] || flag3[k]){
8 continue;
9 }
10 flag1[i]=true;
11 flag2[j]=true;
12 flag3[k]=true;
13 cur[index] = i;
14 if (index==n-1){
15 vector<string> rlt;
16 for (int p=0; p<n; p++){
17 string s="";
18 for (int q=0; q<n; q++){
19 if (cur[p]==q)
20 s+='Q';
21 else s+='.';
22 }
23 rlt.push_back(s);
24 }
25 rlts.push_back(rlt);
26 }
27 else generateResults(rlts,n,index+1,cur,flag1,flag2,flag3);
28 flag1[i]=false;
29 flag2[j]=false;
30 flag3[k]=false;
31 }
32 }
33
34 vector<vector<string> > solveNQueens(int n) {
35 // IMPORTANT: Please reset any member data you declared, as
36 // the same Solution instance will be reused for each test case.
37 vector<vector<string> > rlts;
38 if (n<=0)
39 return rlts;
40 int * cur = new int[n];
41 bool * flag1 = new bool[n];
42 bool * flag2 = new bool[2*n-1];
43 bool * flag3 = new bool[2*n-1];
44 for (int i=0; i<n; i++){
45 flag1[i]=false;
46 cur[i] = 0;
47 }
48 for (int i=0; i<2*n-1; i++){
49 flag2[i]=false;
50 flag3[i]=false;
51 }
52 generateResults(rlts,n,0,cur,flag1,flag2,flag3);
53 delete []cur;
54 delete []flag1;
55 delete []flag2;
56 delete []flag3;
57 return rlts;
58 }
59 };
