#include <stddef.h>
#include <stdio.h>
#include <assert.h>
#include <vector>
#include "squares.h"
struct edge;
struct node {
std::vector<edge> edges;
bool visited;
} nodes[512];
struct edge {
node *nd;
int digit;
edge(node *n, int d) : nd(n), digit(d) {}
};
int seq[1024], iseq[1024], seqi = 0;
bool seq_init = false;
void dfs(node *n, int d) {
if(n->visited) return;
n->visited = true;
int w = (((n - nodes) << 1) | d) & 1023;
seq[seqi] = w;
iseq[w] = seqi++;
dfs(n->edges.front().nd, n->edges.front().digit);
}
std::vector<int> paint(int n) {
if(!seq_init) {
//Create a De Brujn sequence, and store the words in a look up table
for(int w = 0; w < 512; w++) {
nodes[w].edges.push_back(edge(nodes + (((w<<1) | 0) & 511), 0));
nodes[w].edges.push_back(edge(nodes + (((w<<1) | 1) & 511), 1));
nodes[w].visited = false;
}
dfs(nodes+0, 0);
seq_init = true;
}
//Init labels from sequence
std::vector<int> l(n+1);
for(int i = 0; i < n; i++) l[n] = seq[i];
l[n] = 10;
return l;
}
int find_location(int n, std::vector<int> c) {
assert(c.size() == 10);
//Is at edge?
if(c[9] < 0) {
int p = 0;
while(c[p] >= 0) p++;
return n - p;
}
//Calculate word
int w = 0;
for(int i = 0; i < 10; i++) {
assert(c[i] >= 0);
w = (w << 1) | c[i];
}
//Lookup in LUT
// printf("lut %d => %d\n", w, lut[w]);
return iseq[w];
}
