アルゴリズムの問題--嫌いなカエル

//    ，      
//                 
//            ，        
#include 
#include 
#include 
using namespace std;
int r,c,n;

struct PLANT{
    int x,y;
};  //          
//  debug        
PLANT plants[5001]={{2,1},{6,6},{4,2},{2,5},{2,6},{2,7}
,{3,4},{6,1},{6,2},{6,3},{2,3},{6,4},{6,5},{6,7}}; //    5000   
PLANT plant;

//     
bool operator < (const PLANT &p1, const PLANT &p2){
    if(p1.x == p2.x)
        return p1.y < p2.y;
    return p1.x < p2.x;
}

//    ，         
int searchPath(PLANT secPlant, int dX, int dY){
    PLANT plant;
    int steps;
    plant.x = secPlant.x + dX;
    plant.y = secPlant.y + dY;
    steps = 2;
    while(plant.x<=r && plant.x>=1 && plant.y<=c && plant.y>=1){
        if(!binary_search(plants, plants+n, plant)){
            //               ，           
            steps = 0;
            break;
        }
        plant.x += dX;
        plant.y += dY;
        steps++;
    }
    return (steps);
}
void input(){
    r = 6;
    c = 7;
    n = 14;
}
int main(){
    int i,j,dX,dY,pX,pY,steps,max = 2;//max          ，          
    /*scanf("%d %d", &r, &c);     //          
    printf("r=%d, c=%d
", r, c);
    scanf("%d", &n);            //            
    printf("n=%d
", n);
    for(i=0 ; i=1 && pY<=c && pY>=1){    //             
               //printf("(%d, %d)is not the first point of (%d, %d)
", plants[i].x, plants[i].y,plants[j].x,plants[j].y);
               continue;   
            }
            //                        
            //              
            //       dX  i       ，        i   
            if(plants[i].x + (max - 1)*dX > r){
                //printf("x:(%d, %d)is not the start point of the longest way
", plants[i].x, plants[i].y);
                break;
            }
            pY = plants[i].y + (max - 1)*dY;
            if(pY > c || pY < 1){
                //printf("y:(%d, %d)is not the start point of the longest way
", plants[i].x, plants[i].y);
                continue;
            }
            /*printf("the first point (%d, %d)
", plants[i].x, plants[i].y);
            printf("the second point (%d, %d)
", plants[j].x, plants[j].y);*/
            steps = searchPath(plants[j], dX, dY);  //      
            if(steps > max) max = steps;
        }
    }
    if(max == 2) max = 0;
    printf("%d
", max);
}