From e39b2a8ef22c22a8dcc10eeb7de81c26c5c4e957 Mon Sep 17 00:00:00 2001
From: Nao Pross <naopross@thearcway.org>
Date: Sun, 20 Jan 2019 13:02:31 +0100
Subject: Update vector.cpp to use STL std::transform and std::inner_product

---
 vector/vector.cpp | 24 +++++++++++-------------
 1 file changed, 11 insertions(+), 13 deletions(-)

diff --git a/vector/vector.cpp b/vector/vector.cpp
index 8057cdd..260f08f 100644
--- a/vector/vector.cpp
+++ b/vector/vector.cpp
@@ -5,6 +5,7 @@
 
 #include <array>
 #include <algorithm>
+#include <numeric>
 #include <initializer_list>
 
 
@@ -61,10 +62,12 @@ T basic_vec<T, d>::length() const {
 template<typename T, std::size_t d>
 basic_vec<T, d> operator+(const basic_vec<T, d>& rhs, const basic_vec<T, d>& lhs) {
     basic_vec<T, d> out;
-    auto rit = rhs.cbegin(), lit = lhs.cbegin();
-    std::generate(out.begin(), out.end(), [rit, lit] () mutable {
-        return *(rit++) + *(lit++);
-    });
+    
+    std::transform(rhs.begin(), rhs.end(), lhs.begin(), out.begin(),
+        [](const T& r, const T& l) -> T {
+            return r + l;
+        }
+    );
 
     return out;
 }
@@ -72,10 +75,10 @@ basic_vec<T, d> operator+(const basic_vec<T, d>& rhs, const basic_vec<T, d>& lhs
 template<typename T, std::size_t d>
 basic_vec<T, d> operator*(const T& rhs, const basic_vec<T, d>& lhs) {
     basic_vec<T, d> out;
-    auto lit = lhs.cbegin();
 
-    std::generate(out.begin(), out.end(), [rhs, lit] () mutable {
-        return rhs * *(lit++);
+    std::transform(lhs.begin(), lhs.end(), out.begin(), 
+        [rhs](const T& t) -> T {
+            return t * rhs;
     });
 
     return out;
@@ -88,12 +91,7 @@ basic_vec<T, d> operator-(const basic_vec<T, d>& rhs, const basic_vec<T, d>& lhs
 
 template<typename T, std::size_t d>
 T operator*(const basic_vec<T, d>& rhs, const basic_vec<T, d>& lhs) {
-    T res = basic_vec<T, d>::null_element;
-    for (std::size_t i = 0; i < d; i++) {
-        res += rhs[i] * lhs[i];
-    }
-
-    return res;
+    return std::inner_product(rhs.begin(), rhs.end(), lhs.begin(), 0);
 }
 
 template<typename T, std::size_t d>
-- 
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