leet code
2084 - N-Queens II
처음 n==6에서 TLE에 걸렸습니다.
이후 n==8에서 TLE에 걸렸습니다.
해결 방법은 rows, columns, 이미 추가된 queens를 모두 순회하는 것이 아니라
rows, columns 둘 중 하나를 생략할 수 있었습니다.
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57 | #include<algorithm>
class Solution {
public:
int totalNQueens(int n) {
_boardSize = n;
return _totalnq(n);
}
int _totalnq(int n){
if(n==0)
{
vector<vector<int>> a(_queens);
sort(a.begin(), a.end());
for(int i=0; i<_answers.size(); ++i)
{
if(_answers[i] == a) return 0;
}
_answers.push_back(a);
return 1; // 성공조건
}
int cnt = 0;
for(int i=0; i<_boardSize; ++i)
{
if(n==_boardSize && i>_boardSize/2) break;
for(int j=0; j<_boardSize; ++j)
{
if(n==_boardSize && j>_boardSize/2) break;
bool isValid = true;
for(int k=0; k< _queens.size(); ++k)
{
int x1 = _queens[k][0];
int y1 = _queens[k][1];
if(x1 == j || y1 == i || (x1-y1) == (j-i) || (x1+y1) == i+j)
{
isValid = false;
break;
};
}
if(!isValid) continue;
vector<int> a{j, i};
_queens.push_back(a);
cnt += _totalnq(n-1);
_queens.pop_back();
}
}
return cnt;
}
private:
int _board[10][10] = {0, };
vector<vector<int>> _queens;
int _boardSize;
vector<vector<vector<int>>> _answers;
};
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53 | #include<algorithm>
class Solution {
public:
int totalNQueens(int n) {
_boardSize = n;
return _totalnq(n);
}
int _totalnq(int n){
if(n==0)
{
vector<vector<int>> a(_queens);
sort(a.begin(), a.end());
for(int i=0; i<_answers.size(); ++i)
{
if(_answers[i] == a) return 0;
}
_answers.push_back(a);
return 1; // 성공조건
}
int cnt = 0;
int j = n-1;
for(int i=0; i<_boardSize; ++i)
{
bool isValid = true;
for(int k=0; k< _queens.size(); ++k)
{
int x1 = _queens[k][0];
int y1 = _queens[k][1];
if(x1 == j || y1 == i || (x1-y1) == (j-i) || (x1+y1) == i+j)
{
isValid = false;
break;
};
}
if(!isValid) continue;
vector<int> a{j, i};
_queens.push_back(a);
cnt += _totalnq(n-1);
_queens.pop_back();
}
return cnt;
}
private:
int _board[10][10] = {0, };
vector<vector<int>> _queens;
int _boardSize;
vector<vector<vector<int>>> _answers;
};
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