Google Puzzle
1. Solve this cryptic equation， realizing of course that values for M and E
could be interchanged. No leading zeros are allowed.
WWWDOT - GOOGLE = DOTCOM
虽然找到O+L = O 或者 O - 9 -1 = O的规律，但是还是认为自己大脑再行穷举路径太多了。所以重用了自己过去的代码解决了。
//
验证函数
bool IsCorrent( int * dest)
  … {
int wwwdot = dest[ 0 ] * ( 100000 + 10000 + 1000 ) + dest[
1 ] * 100 + dest[ 2 ] * 10 + dest[ 3 ];
int google = dest[ 4 ] * ( 100000 + 100 ) + dest[ 2 ] * (
10000 + 1000 ) + dest[ 5 ] * 10 + dest[ 6 ];
int dotcom = dest[ 1 ] * 100000 + dest[ 2 ] * ( 10000 + 10
) + dest[ 3 ] * 1000 + dest[ 7 ] * 100 + dest[ 8 ];
if (wwwdot - google == dotcom)
  … {
return true ;
 }
else
  … {
return false ;
 }
 }
//
求子集函数
void All( int * src, int currentIndex, int len, int * dest, int
num)
  … {
if (currentIndex == len)
return ;
dest[num ++ ] = src[currentIndex ++ ];
if (num == 9 )
  … {
Perm(dest, 0 , 8 , 9 );
 }
All(src,currentIndex,len,dest,num);
All(src,currentIndex,len,dest,num - 1 );
 }
//
求排列函数
void Perm( int * src, int current, int lesslen, int len)
  … {
if (current == lesslen)
  … {
if (IsCorrent(src))
  … {
for ( int i = 0 ; i < len; i ++ )
  … {
cout << src[i] << " " ;
 }
cout << endl;
 }
 }
for ( int i = current; i < len; i ++ )
  … {
swap(src[i],src[current]);
Perm(src,current + 1 ,lesslen,len);
swap(src[i],src[current]);
 }
 }
最后：
WDOTGLECM分别为7 5 8 9 1 0 6 4 3或7 5 8 9 1 0 3 4 6因为E和M可以互换，所以正解…