rename repo, subdir for yearly challenges

2020/day01/ex2-pure-sort.bash

@@ -0,0 +1,55 @@
+#!/bin/bash
+#
+# ex2-pure-sort.bash: Advent2020 game, day 1/game 2, bash bubble sort.
+
+CMD=${0##*/}
+
+readarray -t numbers
+
+# simple bubble sort for numeric array (ascending)
+# args: 1: the array
+# todo: add a parameter for asc/desc order.
+sort_n() {
+    local -a array=( "$@" )
+    local -i max=$(( ${#array[@]} - 1 ))
+
+    for (( max= $(( ${#array[@]} - 1 )); max > 0; max-- )); do
+        local -i i
+        for (( i=0; i<max; i++ )); do
+            local -i val1=${array[$i]}
+            local -i val2=${array[$((i + 1))]}
+
+            # switch if necessary
+            if (( val1 > val2 )); then
+                local tmp=$val1
+                array[$i]=$val2
+                array[$((i + 1))]=$tmp
+            fi
+        done
+    done
+    echo "${array[@]}"
+}
+
+sorted=( $(sort_n "${numbers[@]}") )
+
+declare -i i j k a b c
+
+for ((i=0; i<${#sorted[@]}; ++i)); do
+	a=$((sorted[i]))
+	for ((j=i+1; j<${#sorted[@]}; ++j)); do
+		b=$((sorted[j]))
+		((a+b > 2020)) && break
+		for ((k=j+1; k<${#sorted[@]}; ++k)); do
+			c=$((sorted[k]))
+			((a+b+c > 2020)) && break
+			if ((a+b+c == 2020)); then
+				printf "${CMD} : %d:%d %d:%d %d:%d sum=%d mul=%d\n" \
+				   $i $a $j $b $k $c \
+				   $((a+b+c)) \
+				   $((a*b*c))
+				break 3
+			fi
+		done
+	done
+done
+exit 0