even more compact code

1 files changed, 6 insertions, 7 deletions

diff --git a/2023/src/day19.cpp b/2023/src/day19.cpp
index 192e066..78306c9 100644
--- a/2023/src/day19.cpp
+++ b/2023/src/day19.cpp
@@ -2,6 +2,7 @@
 #include <functional>
 #include <iostream>
 #include <map>
+#include <numeric>
 #include <regex>
 #include <string>
 #include <vector>
@@ -83,18 +84,16 @@ part1(map<string, tuple<vector<tuple<string, string, long, string>>, string>> ru
 void
 part2(map<string, tuple<vector<tuple<string, string, long, string>>, string>> rules)
 {
-        function<long(map<string, tuple<long, long>>, string)> count = [&](map<string, tuple<long, long>> ranges, const string& name) -> long {
+        function<long(map<string, tuple<long, long>>, string)> count = [&](auto ranges, const string& name) -> long {
                 if ( name == "R" ) {
                         return 0;
                 }
 
                 if ( name == "A" ) {
-                        long result = 1;
-                        for ( const auto& range: ranges ) {
-                                const auto [lo, hi] = range.second;
-                                result *= hi - lo + 1;
-                        }
-                        return result;
+                        return accumulate(ranges.begin(), ranges.end(), 1L, [](auto lhs, auto rhs) {
+                                const auto [lo, hi] = rhs.second;
+                                return lhs * (hi - lo + 1);
+                        });
                 }
 
                 const auto [sub_rules, fallback] = rules[name];