C version, bash cleanup.

day15/Makefile

@@ -15,13 +15,13 @@ output:
 
 compile: ex1-c ex2-c
 
-ex1:
+ex1: ex1-c
 	@$(TIME) ex1.bash 2020 < $(INPUT) 2>&1
-	@#$(TIME) ex1-c < $(INPUT) 2>&1
+	@$(TIME) ex1-c 2020 < $(INPUT) 2>&1
 
-ex2:
+ex2: ex1-c
 	@$(TIME) ex1.bash 30000000 < $(INPUT) 2>&1
-	@#$(TIME) ex2-c < $(INPUT) 2>&1
+	@$(TIME) ex1-c 30000000 < $(INPUT) 2>&1
 
 clean:
 	@rm -f ex1-c ex2-c core

day15/OUTPUT

@@ -1,8 +1,15 @@
-ex1.bash : res=1618
-	time: 0:00.07 real, 0.07 user, 0.00 sys
-	context-switch:	7+1, page-faults: 0+172
+ex1.bash : res[2020]=1618
+	time: 0:00.03 real, 0.02 user, 0.00 sys
+	context-switch:	6+1, page-faults: 0+158
 
-ex3.bash : res=548531
+ex1-c : res[2020]=1618
+	time: 0:00.00 real, 0.00 user, 0.00 sys
+	context-switch:	0+1, page-faults: 0+77
+
+ex1.bash : res[30000000]=548531
 	time: 12:22:02 real, 44488.91 user, 2.70 sys
 	context-switch:	4552388+2, page-faults: 0+98912
 
+ex1-c : res[30000000]=548531
+	time: 0:00.56 real, 0.49 user, 0.06 sys
+	context-switch:	55+1, page-faults: 0+29369

day15/ex1-c.c

@@ -0,0 +1,40 @@
+/* ex1-c: Advent2020 game, day 15/games 1 and 2
+ */
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+int main(ac, av)
+    int ac;
+    char **av;
+{
+    char line[1024], *pval;
+    int target, cur=0, *array;
+    register int diff, previous=-1;
+
+    if (ac != 2) {
+        fprintf(stderr, "usage: %s number\n", *av);
+    }
+    target=atol(*(av+1));
+    array=malloc(sizeof(unsigned long) * target);
+    for (int i=0; i<target; ++i) {
+        array[i]=-1;
+    }
+
+    fgets(line, sizeof line, stdin);
+    pval=strtok(line, ",");
+    do {
+        diff=atoi(pval);
+        array[diff]=cur++;
+    } while (pval=strtok(NULL, ","));
+
+    for (; cur<target; ++cur) {
+        diff = (previous>=0)? cur-previous-1: 0;
+        previous=array[diff];
+        array[diff]=cur;
+    }
+
+    printf("%s : res[%d]=%d\n", *av, target, diff);
+    exit (0);
+}

day15/ex1.bash

@@ -6,7 +6,7 @@ CMD=${0##*/}
 #shopt -s extglob
 
 declare -A prev
-declare -i cur=1 last previous
+declare -i cur=1 previous
 
 
 function print_binary() {
@@ -27,7 +27,6 @@ function print_binary() {
 function print_array() {
 	local -i i
 
-	printf "last: %d\n" "$last"
 	printf "nums:\n"
 	for i in "${!prev[@]}"; do
 		printf " prev[%d] => %d\n" "$i" "${prev[$i]}" >&2
@@ -40,7 +39,6 @@ read -r line
 set -- $line
 while (($# > 0)); do
 	prev[$1]=$cur
-	last=$1
 	((cur++))
 	shift
 done
@@ -53,9 +51,8 @@ for ((previous=0; cur <= TARGET; ++cur)); do
 	fi
 	((previous=prev[$diff]))
 	prev[$diff]=$cur
-	last=$diff
 done
 
-printf "%s : res=%d\n" "$CMD" "$last"
+printf "%s : res[%d]=%d\n" "$CMD" "$TARGET" "$diff"
 
 exit 0