Wrote a function that simulates the destruction of a geoblock.

Pass it the index of the block in state that would be destroyed.
The function will return whatever is left in state after triggering
the destruction of said block.

CMakeLists.txt

@@ -1,5 +1,5 @@
 cmake_minimum_required(VERSION 2.6 FATAL_ERROR)
-list (APPEND CMAKE_MODULE_PATH ${CMAKE_CURRENT_SOURCE_DIR}/cmake/cmake-d)
+list (APPEND CMAKE_MODULE_PATH ${CMAKE_CURRENT_SOURCE_DIR}/cmake/cmake-d/cmake-d)
 project(disgaea_solver D)
 
 add_executable(${PROJECT_NAME}

src/disgaea_solve.d

@@ -1,8 +1,93 @@
 module src.disgaea_solve;
 
-struct Action {
+import std.array;
+import std.algorithm : remove;
+import std.range;
+import std.stdio;
+
+struct GeoPair {
 	char block;
-	char tile;
+	char panel;
 }
 
-Action[] disgaea_solve (
+struct PlyItem {
+	GeoPair[] geo_pair;
+	int start_item;
+}
+
+private int find_starting_pair (GeoPair[] parState) {
+	int[char] seen_panels;
+	foreach (geo; parState) {
+		int* seen_panel = geo.panel in seen_panels;
+		if (seen_panel)
+			++*seen_panel;
+		else
+			seen_panels[geo.panel] = 1;
+	}
+
+	return 0;
+}
+
+private int[] find_all_blocks_on_panel (GeoPair[] parState, char parPanel) {
+	int[] retval;
+	foreach (z, geo; parState) {
+		if (geo.panel == parPanel)
+			retval ~= cast(int)z;
+	}
+	return retval;
+}
+
+private void morph (GeoPair[] parState, char parFrom, char parTo) {
+	foreach (ref geo; parState) {
+		if (geo.panel == parFrom)
+			geo.panel = parTo;
+	}
+}
+
+private GeoPair[] simulate (GeoPair[] parState, int parDestroy) {
+	assert(parDestroy < parState.length);
+	int[] destroyed = [parDestroy];
+	auto state = parState.dup;
+
+	do {
+		assert(!destroyed.empty);
+		const auto current = destroyed.back;
+		destroyed.popBack();
+		auto current_geo = state[current];
+		assert(current >= 0 && current < state.length);
+		state = state.remove(current);
+
+		auto affected = find_all_blocks_on_panel(state, current_geo.panel);
+		morph(state, current_geo.panel, current_geo.block);
+		destroyed ~= affected;
+	} while(!destroyed.empty);
+
+	return state;
+}
+
+private int evaluate_state (GeoPair[] parState, int parStart) {
+	int score = 0;
+	//foreach (geo; parState) {
+	//	switch (geo.block) {
+	//	case '@':
+	//		if (geo.panel
+	//}
+
+	return score;
+}
+
+PlyItem[] disgaea_solve (GeoPair[] parState) {
+	const int starting_index = find_starting_pair(parState);
+	auto new_state = simulate(parState, starting_index);
+
+	writeln("Original state:");
+	foreach (geo; parState) {
+		writef("%s/%s, ", geo.block, geo.panel);
+	}
+	writeln("\nState after running simulation:");
+	foreach (geo; new_state) {
+		writef("%s/%s, ", geo.block, geo.panel);
+	}
+	writeln();
+	return new PlyItem[1];
+}

src/main.d

@@ -13,5 +13,11 @@ int main (string[] parArgs) {
 		return 2;
 	}
 
+	disgaea_solve.disgaea_solve([
+		GeoPair('b', 'r'),
+		GeoPair('y', 'b'),
+		GeoPair('g', 'r'),
+		GeoPair('@', 'g')
+	]);
 	return 0;
 }