# include & lt; stdio.h> 
Int a [21] [21]={0}, count=0, m, n; 
Int main () 
{
Int x, y; 
Void search (int x, int y); 
The scanf (" % d % d % d % d ", & amp; M, & amp; N, & amp; X, & amp; Y); 
A [x] [y]=1; 
A [1] x [x - 2]=1;//will not be able to pass the point of value is set to 1 
A [1] x [x + 2]=1; 
A [x - 2] [x + 1]=1; 
A [1] x [x - 2]=1; 
A [x + 1] [x + 2]=1; 
A [x + 1] [x - 2]=1; 
A [x + 2] [x + 1]=1; 
A [1] x [x + 2]=1; 
Search (0, 0); 
Printf (" % d \ n ", count);//output from (0, 0) to (m, n) points' 
} 
Void search (int x, int y) 
{
If (x> M | | y> N) return;//if x> M or y> N the end of the search 
If (x==m& & Y==n) {count++; return ; }//if reach (m, n) this number 1 
If (a [x] [y + 1)!=1) search (x, y + 1);//if the right can walk to the right to search 
If (a [x + 1] [y]!=1) search (x + 1, y);//if below can walk down the search 
} 

Every time I feel the method should be yes, down to the right, and why the answer right

CodePudding user response:

The subscript have the opportunity to cross;
You enter y with a bit less,

CodePudding user response:

Found the problem, is an obstacle to set has a problem, the subscript should not cross, because I only to the right and down the search, and more than this range will return