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发帖数: 84 | 1 请问下面有一行：
pos = upper & (~(row | ld |rd));
这里为什么要upper&？upper不都是1吗？
class Solution {
public:
int cnt,upper;
int totalNQueens(int n) {
// Start typing your C/C++ solution below
// DO NOT write int main() function
cnt = 0;
upper = (1<
Queen(0,0,0);
return cnt;
}
void Queen(int row,int ld,int rd)
{
int pos,p;
if(row!=upper)
{
pos = upper & (~(row | ld |rd));
while(pos!=0)
{
p = pos & (-pos);
pos = pos - p;
Queen(row+p,(ld+p)<<1,(rd+p)>>1);
}
}
else ++cnt;
}
}; |
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