box max height

#include <iostream>
#define MAX 20

using namespace std;

int x[MAX],y[MAX];
int a[MAX][MAX]={0};
int queue[100];
int front,rear;
int in_degree[MAX]={0};
int dist[MAX]={0};

void find_max_height(){
	int i,v;
	front=-1;
	rear=-1;

	for(i=0;i<MAX;i++){
		if(in_degree[i]==0){
			queue[++rear] =i;
		}
	}
	while(rear!=front){
		 v=queue[++front];

		 for(i=0;i<MAX;i++){
			 if(a[v][i]!=0 && in_degree[i]!=0){
				 if(dist[i]<dist[v]+a[v][i]) dist[i]=dist[v]+a[v][i];
				 in_degree[i]--;
				 if(in_degree[i]==0) queue[++rear]=i;
			 }
		 }
	}
}

int main(){
	int i,j;
	int max=0;

	for(i=0;i<MAX;i++){
		cout<<"["<<i+1<<"] : ";
		cin>>x[i]>>y[i];
	}
	
	for(i=0;i<MAX;i++){
		for(j=i+1;j<MAX;j++){
			if(x[i]>=x[j] && y[i]>=y[j]){
				a[i][j]=1;
				in_degree[j]++;
			}
			else if(x[i]<=x[j] && y[i]<=y[j]) {
				a[j][i]=1;
				in_degree[i]++;
			}
		}
	}
	find_max_height();

	for(i=0;i<MAX;i++){
		if(dist[i]>max) max=dist[i];
	}
	cout<<"최고높이: "<<max+1<<endl;
}