From 24c28577f55e83e17a7f488c2dc7d4454a6d8348 Mon Sep 17 00:00:00 2001
From: Avril <flanchan@cumallover.me>
Date: Sat, 5 Dec 2020 13:37:21 +0000
Subject: [PATCH] day5

---
 Makefile      |  12 +++--
 day5/Makefile |  41 ++++++++++++++++
 day5/day5.c   | 132 ++++++++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 180 insertions(+), 5 deletions(-)
 create mode 100644 day5/Makefile
 create mode 100644 day5/day5.c

diff --git a/Makefile b/Makefile
index afd1163..f2852bf 100644
--- a/Makefile
+++ b/Makefile
@@ -1,4 +1,4 @@
-COMMON_OPT_FLAGS?= -O3 -march=native -pipe -flto \
+COMMON_OPT_FLAGS?= -DFROM_MAIN -O3 -march=native -pipe -flto \
 	 -march=native -fgraphite -fopenmp -floop-parallelize-all -ftree-parallelize-loops=4 \
 	 -floop-interchange -ftree-loop-distribution -floop-strip-mine -floop-block \
 	 -fno-stack-check -fno-strict-aliasing 
@@ -9,18 +9,20 @@ LD_OPT_FLAGS?=-O3 -flto
 
 COMMON_FLAGS=-Wall -pedantic $(COMMON_OPT_FLAGS)
 
-CFLAGS?=$(COMMMON_FLAGS) --std=gnu11 $(C_OPT_FLAGS)
-CXXFLAGS?=$(COMMON_FLAGS) --std=gnu++20 $(CXX_OPT_FLAGS)
-LDFLAGS?=$(LD_OPT_FLAGS)
+CFLAGS+=$(COMMON_FLAGS) --std=gnu11 $(C_OPT_FLAGS)
+CXXFLAGS+=$(COMMON_FLAGS) --std=gnu++20 $(CXX_OPT_FLAGS)
+LDFLAGS+=$(LD_OPT_FLAGS)
 
 DAYS= $(wildcard day*)
 
+ENV= CFLAGS="$(CFLAGS)" CXXFLAGS="$(CXXFLAGS)" LDFLAGS="$(LDFLAGS)"
+
 .PHONY: all
 
 all: $(addsuffix /part2,$(DAYS))
 
 day%/part2: day%
-	cd $< && $(MAKE)
+	cd $< && $(ENV) $(MAKE)
 
 clean:
 	for d in $(DAYS); do pushd $$d && $(MAKE) clean && popd; done
diff --git a/day5/Makefile b/day5/Makefile
new file mode 100644
index 0000000..32a9fdf
--- /dev/null
+++ b/day5/Makefile
@@ -0,0 +1,41 @@
+SRC:= day5.c
+
+OPT_FLAGS?= -O3 -march=native -pipe -flto \
+	 -march=native -fgraphite -fopenmp -floop-parallelize-all -ftree-parallelize-loops=4 \
+	 -floop-interchange -ftree-loop-distribution -floop-strip-mine -floop-block \
+	 -fno-stack-check -fno-strict-aliasing 
+
+CFLAGS?=$(OPT_FLAGS)
+LDFLAGS?=-O3 -flto
+
+CFLAGS+= -Wall -pedantic --std=gnu11 
+
+.PHONY: all
+all: part1 part2
+
+.PHONY: test
+test: part1-test part2-test
+
+inpu%.h: inpu%
+	@rm -f $@
+	while read line; do \
+		echo "\"$$line\"," >> $@; \
+	done < $<
+
+part1-test: $(SRC) | input-test.h
+	$(CC) $^ -DTEST -DDEBUG $(CFLAGS) -o $@ $(LDFLAGS)
+
+part2-test: $(SRC) | input-test.h
+	$(CC) $^ -DTEST -DDEBUG -DPART2 $(CFLAGS) -o $@ $(LDFLAGS)
+
+part1: $(SRC) | input.h
+	$(CC) $^ $(CFLAGS) -o $@ $(LDFLAGS)
+	strip $@
+
+part2: $(SRC) | input.h
+	$(CC) $^ -DPART2 $(CFLAGS) -o $@ $(LDFLAGS)
+	strip $@
+
+clean:
+	rm -f part{1,2}{,-test}
+	rm -f input{,-test}.h
diff --git a/day5/day5.c b/day5/day5.c
new file mode 100644
index 0000000..1090845
--- /dev/null
+++ b/day5/day5.c
@@ -0,0 +1,132 @@
+#include <stddef.h>
+#include <stdint.h>
+#include <stdlib.h>
+#include <stdio.h>
+
+#define _cold __attribute__((cold, noinline))
+#define noreturn __attribute__((noreturn)) void
+
+#ifdef DEBUG
+#define dlog(...) fprintf(stderr, "[debug]" __VA_ARGS__)
+#else
+inline static void do_nothing(int _n, ...) {}
+#define dlog(...) do { if(0) { do_nothing(0 __VA_OPT__(,) __VA_ARGS__); } } while(0)
+#endif
+
+noreturn static _cold panic(const char* msg)
+{
+	fputs(msg, stderr);
+	fputc('\n', stderr);
+	abort();
+}
+
+typedef struct sloc {
+	int row;
+	int column;
+
+	int id;
+} seat_t;
+
+static const char* input[] = {
+#ifdef TEST
+#include "input-test.h"
+#else
+#include "input.h"
+#endif
+};
+
+#define input_sz (sizeof(input) / sizeof(char*))
+
+
+#define ROW_MAX 128
+#define COL_MAX 8
+
+inline static void seat_calc_id(seat_t* restrict s)
+{
+	s->id = (s->row * 8) + s->column;
+}
+
+
+static int sbsearch(const char* direct, size_t len, int max)
+{
+	int min = 0;
+#define diff (1 + (max - min))
+	for(size_t i=0;i<len;i++)
+	{
+		dlog("%c: min = %d, max = %d\n", direct[i], min, max);
+		switch(direct[i])
+		{
+		case 0: 
+			panic("string overflow");
+		// lower half
+		case 'F':
+		case 'L':
+			max -= diff / 2;
+			if(diff==1) return min;
+			break;
+		// upper half
+		case 'R':
+		case 'B':
+			min += diff / 2;
+			if(diff==1) return max;
+			break;
+		}
+	}
+	panic("bsearch failed");
+#undef diff
+}
+
+static seat_t pbsearch(const char* str)
+{
+	seat_t seat = {
+		.row = (int)sbsearch(str, 7, ROW_MAX-1),
+		.column = (int)sbsearch(str+7, 3, COL_MAX-1),
+	};
+	seat_calc_id(&seat);
+	return seat;
+}
+
+#ifdef PART2
+static int _seat_cmp(const void* ptr, const void* ptr2)
+{
+	const seat_t *s1 = ptr;
+	const seat_t *s2 = ptr2;
+	return    s1->id < s2->id ? -1 
+		: s1->id > s2->id ? 1
+		: 0;
+}
+#endif
+
+
+int main()
+{
+	int max=0;
+	seat_t seats[input_sz];
+	for(size_t i=0;i<input_sz;i++)
+	{
+		dlog("Testing %s\n", input[i]);
+		seat_t seat = seats[i] = pbsearch(input[i]);
+		int id = seat.id;
+		dlog(" -> { .row = %d, .column = %d, .id = %d }\n", seat.row, seat.column, seat.id);
+		if(id>max) max = id;
+	}
+#ifdef PART2
+	qsort(seats, input_sz, sizeof(seat_t), &_seat_cmp);
+	for(size_t i=1; i<input_sz;i++)
+	{
+		seat_t prev = seats[i-1];
+		seat_t this = seats[i];
+#define diff (this.id - prev.id)
+		if(diff == 2)
+		{
+			printf("%d\n", prev.id+1);
+			return 0;
+		}
+	}
+	fprintf(stderr, "Failed to find id\n");
+	return 1;
+#else
+	printf("%d\n", max);
+#endif
+	return 0;
+}