Solution1:我的答案
教科书一样的回溯法
《程序员面试金典》中有一道一毛一样的题啊!
class Solution {
public:
int totalNQueens(int n) {
vector<int> temp;
int num = 0;
my_count(temp, num, n);
return num;
}
void my_count(vector<int> temp, int &num, int n) { //temp临时答案,num总次数,n棋盘大小
if (temp.size() == n) {
num++;
return;
} else {
for (int i = 0; i < n; i++) {
temp.push_back(i);
if (isValid(temp))
my_count(temp, num, n);
temp.pop_back();
}
}
}
bool isValid(vector<int>& temp) {
if (temp.size() == 1) return true;
else {
int k = temp.size();
for (int i = 0; i < temp.size() - 1; i++) {
if(temp[i] == temp[k - 1] || abs(i - k + 1) == abs(temp[i] - temp[k - 1]))
return false;
}
return true;
}
}
};