From fcb57c3b4ebb7bbf25d50f9080766fce0f39f404 Mon Sep 17 00:00:00 2001
From: David Allemang <allemang.d@gmail.com>
Date: Wed, 20 Nov 2019 12:29:01 -0500
Subject: [PATCH] working implementation

---
 CMakeLists.txt |  4 +++
 main.cpp       | 75 ++++++++++++++++++++++++++++++++++++++------------
 2 files changed, 62 insertions(+), 17 deletions(-)

diff --git a/CMakeLists.txt b/CMakeLists.txt
index 21cba0a..8910e1e 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -2,5 +2,9 @@ cmake_minimum_required(VERSION 3.14)
 project(hpc)
 
 set(CMAKE_CXX_STANDARD 17)
+set(CMAKE_CXX_FLAGS_RELEASE "-O2")
+
+find_package(OpenMP)
 
 add_executable(hpc main.cpp)
+target_link_libraries(hpc PUBLIC OpenMP::OpenMP_CXX)
diff --git a/main.cpp b/main.cpp
index 08c777d..fa0419e 100644
--- a/main.cpp
+++ b/main.cpp
@@ -1,21 +1,25 @@
 #include <iostream>
 #include <vector>
+#include <iomanip>
+#include <chrono>
 
 using Gens=std::vector<int>;
 using Table=std::vector<Gens>;
 
-void pp(const Gens &g) {
+void pp(const Gens &g, int w) {
     for (const auto &e : g) {
-        std::cout << e << " ";
+        std::cout << std::setw(w) << e << " ";
     }
     std::cout << std::endl;
 }
 
 void pp(const Table &t) {
     std::cout << "| table:" << std::endl;
-    for (const auto &g : t) {
-        std::cout << "| ";
-        pp(g);
+    int w = 3;
+
+    for (size_t i = 0; i < t.size(); ++i) {
+        std::cout << std::setw(w) << i << " | ";
+        pp(t[i], w);
     }
 }
 
@@ -41,8 +45,31 @@ void add_row(const int ngens, const std::vector<Gens> &rels,
     }
 }
 
+int add_coset(const int ngens, const std::vector<Gens> &rels,
+    Table &cosets, std::vector<Table> &reltables,
+    Table &starts, Table &ends,
+    int coset_scan_hint) {
+
+    int C = cosets.size();
+
+    for (int c = coset_scan_hint; c < C; ++c) {
+        std::vector<int> &row = cosets[c];
+        for (int g = 0; g < ngens; ++g) {
+            if (row[g] == -1) {
+                row[g] = C;
+                add_row(ngens, rels, cosets, reltables, starts, ends);
+                cosets[C][g] = c;
+                return c;
+            }
+        }
+    }
+
+    return -1;
+}
+
+
 /**
- * @return true if anything was learned
+ * learn until it can't
  */
 void learn(Table &coset, const std::vector<Gens> &rels,
     std::vector<Table> &reltables, Table &starts, Table &ends) {
@@ -63,27 +90,28 @@ void learn(Table &coset, const std::vector<Gens> &rels,
 
                 if (s == e - 1) continue;
 
-                while (row[s] == -1) {
-                    int &lookup = coset[row[s]][rel[s]];
+                while (row[s + 1] == -1) {
+                    const int &lookup = coset[row[s]][rel[s]];
                     if (lookup < 0) break;
 
-                    row[s] = lookup;
                     s++;
+                    row[s] = lookup;
                 }
 
-                while (row[e] == -1) {
-                    int &lookup = coset[row[e]][rel[e - 1]];
+                while (row[e - 1] == -1) {
+                    const int &lookup = coset[row[e]][rel[e - 1]];
                     if (lookup < 0) break;
 
-                    row[e] = lookup;
                     e--;
+                    row[e] = lookup;
                 }
 
                 if (s == e - 1) {
                     complete = false;
 
-                    coset[row[s]][rel[s]] = rel[row[e]];
-                    coset[row[e]][rel[s]] = rel[row[s]];
+                    const int &gen = rel[s];
+                    coset[row[s]][gen] = row[e];
+                    coset[row[e]][gen] = row[s];
                 }
 
                 starts[r][c] = s;
@@ -109,17 +137,30 @@ Table solve_tc(int ngens, const Gens &subgens, const std::vector<Gens> &rels) {
         cosets[0][gen] = 0;
     }
 
+    int coset_scan_hint = 0;
+    while (coset_scan_hint >= 0) {
+        learn(cosets, rels, reltables, starts, ends);
+        coset_scan_hint = add_coset(ngens, rels, cosets, reltables, starts, ends, coset_scan_hint);
+    }
+
     return cosets;
 }
 
 int main() {
-    auto cosets = solve_tc(3, {0, 1}, {
-        {0, 1, 0, 1, 0, 1, 0, 1},
+    auto s = std::chrono::system_clock::now();
+    auto cosets = solve_tc(4, {}, {
+        {0, 1, 0, 1, 0, 1, 0, 1, 0, 1},
         {1, 2, 1, 2, 1, 2},
+        {2, 3, 2, 3, 2, 3},
         {0, 2, 0, 2},
+        {0, 3, 0, 3},
+        {1, 3, 1, 3},
     });
+    auto e = std::chrono::system_clock::now();
+    std::chrono::duration<float> diff = e - s;
+    std::cout << diff.count() << "s" << std::endl;
 
-    pp(cosets);
+//    pp(cosets);
 
     return 0;
 }