queens 要求最优的算法最好是算的时间不要超过１ｓ

[inlin]

Queens

Time Limit: 1 Seconds Memory Limit: 32768 K

Total Submit:7 Accepted:1

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Description

You are to find the number of different combinations of placement of N queens on the NxN board. Every queen should NOT attack another (i.e. there should be no two figures sharing the same vertical, horizontal or diagonal.

Input

Number 1<=N<=14.
NOTE:Input is terminated when N=0.

Output

The number of valid combinations.

Sample Input


8
Sample Output


92



算到ｎ＝14就行了

[inlin]

这是我的程序我还想再优化应该怎么改？


#include<iostream>
using namespace std;

const int n = 14 ;
const int n_sub = n - 1 ;
int queen[n] ;
bool row[n] ;
bool passive[2*n-1] ;
bool negative[2*n-1] ;

int main()
{
int cur = 0 ;
int n;
bool flag = false ;
queen[0] = -1 ;

cin>>n;
if(n==0) exit(0);
else
if(n>0&&n<=14)
{
int count = 0 ;
while(cur>=0)
{
while(cur>=0 && queen[cur]<n && !flag)
{
queen[cur]++ ;
if(queen[cur] >= n) {
queen[cur] = -1 ;
cur-- ;
if(cur>=0) {
row[queen[cur]] = false ;
passive[queen[cur] + cur] = false ;
negative[n_sub + cur - queen[cur]] = false ;
}
}
else {
if(row[queen[cur]] == false) {
flag = true ;
if( passive[queen[cur] + cur] == true || negative[n_sub + cur - queen[cur]] == true) {
flag = false ;
}
else
flag = true ;
if(flag) {
if(cur == n-1)
{

count++ ;
}
row[queen[cur]] = true ;
passive[queen[cur] + cur] = true ;
negative[n_sub + cur - queen[cur]] = true ;
cur++ ;
if(cur >= n) {
cur-- ;
row[queen[cur]] = false ;
passive[queen[cur] + cur] = false ;
negative[n_sub + cur - queen[cur]] = false ;
}
flag = false ;
}
}
}
}
}
cout<<count<<endl ;
}
return 0 ;
}