Artemis: Proposed changes for increased performance

src/datastructures/list.cc

@@ -29,13 +29,12 @@ OpsList::Shuffle(std::list<int> &l) {
  * @param end the end index of the slice (exclusive)
  * @return a new list with the elements of l sliced
  */
-std::list<int>
-OpsList::Slice(std::list<int> &l, int start, int end) {
+std::list<int> OpsList::Slice(std::list<int> &l, int start, int end) {
   std::list<int> ret;
-  for (int i = start; i < end; i++) {
-    std::list<int>::iterator it = l.begin();
-    std::advance(it, i);
-    ret.push_back(*it);
+  auto it = l.begin();
+  std::advance(it, start);
+  for (int i = start; i < end && it != l.end(); i++) {
+    ret.push_back(*it++);
   }
   return ret;
-}
+}

src/datastructures/vector.cc

@@ -1,3 +1,4 @@
+#include <algorithm>
 #include "vector.h"
 
 void
@@ -55,20 +56,9 @@ OpsVector::SearchVector(std::vector<int> &v, int n) {
  * @param v Vector to sort.
  * @return The sorted vector.
  */
-std::vector<int>
-OpsVector::SortVector(std::vector<int> &v) {
-  std::vector<int> ret(v);
-
-  for (int i = 0; i < (int) ret.size(); i += 1) {
-    for (int j = 0; j < (int) ret.size() - 1; j += 1) {
-      if (ret[j] > ret[j + 1]) {
-        int temp = ret[j];
-        ret[j] = ret[j + 1];
-        ret[j + 1] = temp;
-      }
-    }
-  }
-  return ret;
+std::vector<int> OpsVector::SortVector(std::vector<int> &v) {
+  std::sort(v.begin(), v.end());
+  return v;
 }
 
 /**
@@ -94,8 +84,7 @@ OpsVector::ReverseVector(std::vector<int> &v) {
  * @param n Number of elements to rotate by.
  * @return The rotated vector.
  */
-std::vector<int>
-OpsVector::RotateVector(std::vector<int> &v, int n) {
+std::vector<int> OpsVector::RotateVector(std::vector<int> &v, int n) {
   std::vector<int> ret;
 
   for (int i = n; i < (int) v.size(); i += 1) {
@@ -126,4 +115,4 @@ OpsVector::MergeVectors(std::vector<int> &v1, std::vector<int> &v2) {
   }
 
   return ret;
-}
+}

src/math/vectoralgebra.cc

@@ -32,23 +32,22 @@ MathVectorAlgebra::Cubic(int a, int b, int c, int d, std::vector<double> &x) {
  *
  * @return Pointer to array of y values (output)
  */
-std::vector<double>
-MathVectorAlgebra::Convolve(int offset, std::vector<double> &h, std::vector<double> &x) {
+std::vector<double> MathVectorAlgebra::Convolve(int offset, std::vector<double> &h, std::vector<double> &x) {
   int m = h.size();
   int n = x.size();
-  int sum_h = 0;
-  std::vector<double> y = std::vector<double>(n);
+  double sum_h = 0;
+  std::vector<double> y(n, 0);
   for (int i = 0; i < m; i += 1) {
     sum_h += std::abs(h[i]);
   }
   if (sum_h == 0) {
     sum_h = 1;
   }
   for (int i = 0; i < n; i += 1) {
-    y[i] = 0;
     for (int j = 0; j < m; j += 1) {
-      if (i - offset + j >= 0 && i - offset + j < n) {
-        y[i] += h[j] * x[i - offset + j] / sum_h;
+      int idx = i - offset + j;
+      if (idx >= 0 && idx < n) {
+        y[i] += h[j] * x[idx] / sum_h;
       }
     }
   }

src/strings/strops.cc

@@ -2,12 +2,7 @@
 
 std::string
 StrOps::ReverseString(std::string &s) {
-  std::string ret;
-
-  for (std::string::reverse_iterator rit = s.rbegin(); rit != s.rend(); ++rit) {
-    ret.insert(ret.end(), *rit);
-  }
-  return ret;
+  return {s.crbegin(), s.crend()};
 }
 
 bool
@@ -18,4 +13,4 @@ StrOps::IsPalindrome(const std::string &s) {
   }
 
   return false;
-}
+}