poj 百练1088滑雪路线问题 动态规划

#include <stdio.h>
#include <stdlib.h>

#define NUM 105

int h[NUM][NUM];
struct Node{
int x,y;
int height;
};
struct Node nodes[NUM*NUM];
int cmp(const void* a,const void *b){
struct Node aa,bb;
aa=*((struct Node*)a);
bb=*((struct Node*)b);
return aa.height-bb.height;
}
int steps[NUM][NUM];
void init(){
int i,j;
for(i=0;i<NUM;i++){
for(j=0;j<NUM;j++){
steps[i][j]=1;
}
}
}
int  main(){
int r,c;
scanf("%d %d",&r,&c);
int index=0;
int i,j;
for(i=1;i<=r;i++){
for(j=1;j<=c;j++){
int t;
scanf("%d",&t);
h[i][j]=t;
nodes[index].x=i;
nodes[index].y=j;
nodes[index].height=t;
index++;
}
}
qsort(nodes,index,sizeof(struct Node),cmp);
init();
int max=1;
int k;
for(k=0;k<index;k++){
int x=nodes[k].x;
int y=nodes[k].y;
//up
if(x>1&&h[x-1][y]>h[x][y]&&steps[x-1][y]<steps[x][y]+1){
steps[x-1][y]=steps[x][y]+1;
}
//right
if(y<c&&h[x][y+1]>h[x][y]&&steps[x][y+1]<steps[x][y]+1){
steps[x][y+1]=steps[x][y]+1;
}
//down
if(x<r&&h[x+1][y]>h[x][y]&&steps[x+1][y]<steps[x][y]+1){
steps[x+1][y]=steps[x][y]+1;
}
//left
if(c>1&&h[x][y-1]>h[x][y]&&steps[x][y-1]<steps[x][y]+1){
steps[x][y-1]=steps[x][y]+1;
}
}
int ii,jj;
for(ii=1;ii<=r;ii++){
for(jj=1;jj<=c;jj++){
if(steps[ii][jj]>max)
max=steps[ii][jj];
}
}
printf("%d\n",max);
return 0;
}