TLE

#include <bits/stdc++.h>
#define LL long long

using namespace std;

int n,g[2][61][21][21][21][21];
int dx[9] = {0,1,-1,0,0,2,-2,0,0};
int dy[9] = {0,0,0,1,-1,0,0,2,-2};

struct node{int x1,y1,x2,y2,s;bool f;};

int ab(int x1,int y1,int x2,int y2,int al,int be,int s,bool f)
{
	if(s > 3*n) return 1e9;
	if(x1 == x2 && y1 == y2) return f ? s : 1e9;
	//if(~g[f][s][x1][y1][x2][y2]) return g[f][s][x1][y1][x2][y2];
	//int ans;
	if(f)
	{
		//ans = 0;
		for (int i = 1;i <= 4;i++)
		{
			int nx = x1+dx[i],ny = y1+dy[i];
			if(nx < 1 || ny < 1 || nx > n || ny > n) continue;
			//ans = max(ans,ab(nx,ny,x2,y2,al,be,s+1,!f));
			al = max(al,ab(nx,ny,x2,y2,al,be,s+1,!f));
			if(al >= be) break;
		}
	}
	else
	{
		//ans = 1e9;
		for (int i = 1;i <= 8;i++)
		{
			int nx = x2+dx[i],ny = y2+dy[i];
			if(nx < 1 || ny < 1 || nx > n || ny > n) continue;
			//ans = min(ans,ab(x1,y1,nx,ny,al,be,s+1,!f));
			be = min(be,ab(x1,y1,nx,ny,al,be,s+1,!f));
			if(al >= be) break;
		}
	}
	return f ? al : be;
	//return g[f][s][x1][y1][x2][y2] = ans;
}

int main()
{
	int r1,c1,r2,c2;cin >> n >> r1 >> c1 >> r2 >> c2;
	if(abs(r1-r2)+abs(c1-c2) == 1) cout << "WHITE 1" << '\n';
	else
	{
		memset(g,-1,sizeof(g));
		cout << "BLACK " << ab(r1,c1,r2,c2,-1e9,1e9,0,1);
	}
	return 0;
}

WA

#include <bits/stdc++.h>
#define LL long long

using namespace std;

int n,g[2][61][21][21][21][21];
int dx[9] = {0,1,-1,0,0,2,-2,0,0};
int dy[9] = {0,0,0,1,-1,0,0,2,-2};

struct node{int x1,y1,x2,y2,s;bool f;};

int ab(int x1,int y1,int x2,int y2,int al,int be,int s,bool f)
{
	if(s > 3*n) return 1e9;
	if(x1 == x2 && y1 == y2) return f ? s : 1e9;
	if(~g[f][s][x1][y1][x2][y2]) return g[f][s][x1][y1][x2][y2];
	if(f)
	{
		for (int i = 1;i <= 4;i++)
		{
			int nx = x1+dx[i],ny = y1+dy[i];
			if(nx < 1 || ny < 1 || nx > n || ny > n) continue;
			al = max(al,ab(nx,ny,x2,y2,al,be,s+1,!f));
			if(al >= be) break;
		}
	}
	else
	{
		for (int i = 1;i <= 8;i++)
		{
			int nx = x2+dx[i],ny = y2+dy[i];
			if(nx < 1 || ny < 1 || nx > n || ny > n) continue;
			be = min(be,ab(x1,y1,nx,ny,al,be,s+1,!f));
			if(al >= be) break;
		}
	}
	return g[f][s][x1][y1][x2][y2] = (f ? al : be);
}

int main()
{

	int r1,c1,r2,c2;cin >> n >> r1 >> c1 >> r2 >> c2;
	if(abs(r1-r2)+abs(c1-c2) == 1) cout << "WHITE 1" << '\n';
	else
	{
		memset(g,-1,sizeof(g));
		cout << "BLACK " << ab(r1,c1,r2,c2,-1e9,1e9,0,1);
	}
	return 0;
}