From 28c6c83641191868f4880c606b83bf8c7798e91c Mon Sep 17 00:00:00 2001
From: Avril <flanchan@cumallover.me>
Date: Sun, 6 Dec 2020 11:43:43 +0000
Subject: [PATCH] day6: part1

---
 day6/Makefile | 30 +++++++++++++++++++
 day6/day6.c   | 83 +++++++++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 113 insertions(+)
 create mode 100644 day6/Makefile
 create mode 100644 day6/day6.c

diff --git a/day6/Makefile b/day6/Makefile
new file mode 100644
index 0000000..9da2186
--- /dev/null
+++ b/day6/Makefile
@@ -0,0 +1,30 @@
+
+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 
+
+inpu%.h: inpu%
+	@rm -f $@
+	while read line; do \
+		echo "\"$$line\"," >> $@; \
+	done < $<
+
+part1: day6.c | input.h
+	$(CC) $< $(CFLAGS) -o $@ $(LDFLAGS)
+
+part1-test: day6.c | input-test.h
+	$(CC) $< -DTEST $(CFLAGS) -o $@ $(LDFLAGS)
+	
+clean:
+	rm -f part{1,2}{,-test}
+	rm -f input.h
+
diff --git a/day6/day6.c b/day6/day6.c
new file mode 100644
index 0000000..bec1bf3
--- /dev/null
+++ b/day6/day6.c
@@ -0,0 +1,83 @@
+
+#include <stdbool.h>
+#include <stdlib.h>
+#include <stdio.h>
+#include <string.h>
+
+#if defined(TEST) && !defined(DEBUG)
+#define DEBUG
+#endif
+
+static const char* const answers[] = {
+#ifdef TEST
+#include "input-test.h"
+#else
+#include "input.h"
+#endif
+};
+
+#define  answers_sz (sizeof(answers) / sizeof(char*))
+
+#define NUM_QUESTIONS 26
+
+inline static char assert_in_bound(char i)
+{
+	register int x=(int)i;
+	if(x<0 || x>=NUM_QUESTIONS) {
+		fprintf(stderr, "Fatal error: char '%c' (%d) is not in range 0..%d\n", i, x, NUM_QUESTIONS);
+		abort();
+	}
+	return i;
+}
+
+static void populate(const char* from, bool answered [restrict NUM_QUESTIONS]) //wtf is this syntax? `bool* restrict a` -> `bool a[restrict N]`????
+{
+	while(*from)
+		answered[(int)assert_in_bound((*from++)-'a')] = true;
+}
+
+static size_t count_ans(const bool answered[restrict NUM_QUESTIONS]) 
+{
+	register size_t j=0;
+	for(register size_t i=0;i<NUM_QUESTIONS;i++)
+		j+= answered[i] ? 1 : 0;
+	return j;
+}
+
+inline static size_t reset(bool* restrict pop, bool answered[restrict NUM_QUESTIONS], size_t* restrict group_count)
+{
+	register size_t fullcnt=0;
+	if(pop) {
+		fullcnt = (*group_count = count_ans(answered));
+#ifdef DEBUG
+		fprintf(stderr, "Last group: %lu (fcnt %lu)\n" , *group_count, fullcnt);
+#endif
+	}
+	pop = false;
+	memset(answered,0, NUM_QUESTIONS);
+	return fullcnt;
+}
+
+int main()
+{
+	bool answered[NUM_QUESTIONS] = {false};
+	size_t group_counts[answers_sz+1] = {0};
+	size_t fullcnt=0;
+	bool pop=false;
+
+	for(size_t i=0,j=0;i<answers_sz;i++)
+	{
+		const char* current = answers[i];
+		if(*current) {
+			populate(current, answered);
+			pop=true;
+		} else {
+			fullcnt += reset(&pop, answered, &group_counts[j++]);
+		}
+
+	}
+	fullcnt+= reset(&pop, answered, group_counts +answers_sz);
+	printf("%lu\n", fullcnt);
+
+	return 0;
+}