> # include <iostream.h>
> # include <stdlib.h>
> # include <memory.h>
> const int T=100*100;
> struct Point{
> 	int r,c;
> 	int h;
> }Snowarea[T];
> int snowlen[T][4]={0};//记录第i个点向四个方向0左1右2上3下最长滑雪道长度
> 
> int cmp(const void*a,const void*b){
> 	return ((Point*)a)->h-((Point*)b)->h;
> }
> int cmpint(const void*a,const void*b){
> 	return *((int*)b)-*((int*)a);
> }
> 
> void Findlen(int);
> bool CanGo(int,int,int);
> int max(int);
> void main(){	
> 	int row,col;
> 	int i,j,k;	
> 	cin>>row>>col;
> 	k=0;
> 	for (i=1;i<=row;i++){
> 		for (j=1;j<=col;j++){
> 			Snowarea[k].r=i;
> 			Snowarea[k].c=j;
> 			cin>>Snowarea[k].h;
> 			k++;
> 		}
> 	}
> 	qsort(Snowarea,row*col,sizeof(Point),cmp);
> 	Findlen(row*col);
> }
> void Findlen(int n){
> 	int i,j;	
> 	memset(snowlen,0,sizeof(int)*n*4);
> 	for (i=1;i<n;i++){
> 		for (j=i-1;j>=0;j--){//point j below point i
> 			if (Snowarea[i].h==Snowarea[j].h)	continue;
> 			if (CanGo(i,j,0)==true)		snowlen[i][0]=max(j)+1;
> 			if (CanGo(i,j,1)==true)		snowlen[i][1]=max(j)+1;
> 			if (CanGo(i,j,2)==true)		snowlen[i][2]=max(j)+1;
> 			if (CanGo(i,j,3)==true)		snowlen[i][3]=max(j)+1;
> 		}
> 	}
> 	qsort(snowlen,n*4,sizeof(int),cmpint);
> 	cout<<snowlen[0][0]+1<<endl;
> }
> 
> bool CanGo(int i,int j,int direction){
> 	switch (direction){
> 	case 0: if (Snowarea[j].r==Snowarea[i].r 
> 				&& Snowarea[j].c==Snowarea[i].c-1)	return true;
> 			else	return false;
> 			break;
> 	case 1: if (Snowarea[j].r==Snowarea[i].r 
> 				&& Snowarea[j].c==Snowarea[i].c+1) return true;
> 			else	return false;
> 			break;
> 	case 2: if (Snowarea[j].r==Snowarea[i].r-1 
> 				&& Snowarea[j].c==Snowarea[i].c) return true;
> 			else	return false;
> 			break;
> 	case 3: if (Snowarea[j].r==Snowarea[i].r+1 
> 				&& Snowarea[j].c==Snowarea[i].c) return true;
> 			else	return false;
> 			break;
> 	}
> }
> 
> int max(int j){	
> 	qsort(snowlen[j],4,sizeof(int),cmpint);
> 	return snowlen[j][0];
> }

• 就是dp (0) frkstyc 2006-04-10 21:36:44