N-Queens II

Desicription

Follow up for N-Queens problem.

Now, instead outputting board configurations, return the total number of distinct solutions.

fuck

Solution

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class Solution {
private:
int res = 0;
public:
int totalNQueens(int n) {
vector<int> state(n, -1);
dfs(state, 0);
return res;
}
void dfs(vector<int>& state, int row){
int n = state.size();
if(row == n){
res++;
return ;
}
for(int col = 0; col < n; col++){
if(isVaild(state, row, col)){
state[row] = col;
dfs(state, row+1);
state[row] = -1;
}
}
}
bool isVaild(vector<int>& state, int row, int col){
for(int i = 0; i < row; i++){
if(state[i] == col || abs(row - i) == abs(col - state[i]))
return 0;
}
return 1;
}
};