diff --git a/c/src/p0015.c b/c/src/p0015.c
index c5d334f1..898bfebb 100644
--- a/c/src/p0015.c
+++ b/c/src/p0015.c
@@ -22,10 +22,8 @@ How many such routes are there through a 20×20 grid?
 #include "include/macros.h"
 #include "include/math.h"
 
-#define lattice_paths(height, width) (n_choose_r(height + width, height))
-
 uint64_t EMSCRIPTEN_KEEPALIVE p0015() {
-    return lattice_paths(20, 20);
+    return n_choose_r(40, 20);
 }
 
 PROGRAM_TAIL("%" PRIu64, p0015)
diff --git a/cplusplus/src/p0013.cpp b/cplusplus/src/p0013.cpp
index aa27e153..b462c0f0 100644
--- a/cplusplus/src/p0013.cpp
+++ b/cplusplus/src/p0013.cpp
@@ -217,23 +217,19 @@ static const uint64_t ten18 = 1000000000000000000;
 static const uint64_t ten10 = 10000000000;
 
 uint64_t EMSCRIPTEN_KEEPALIVE p0013() {
-    uint64_t high = 0, med = 0, low = 0;
+    uint64_t arr[3] = { 0 };
     for (uint8_t i = 0; i < 100; ++i) {
-        low += numbers[i][2];
-        med += numbers[i][1];
-        high += numbers[i][0];
-        if (low > ten18) {
-            med += low / ten18;
-            low %= ten18;
-        }
-        if (med > ten18) {
-            high += med / ten18;
-            med %= ten18;
-        }
+        for (uint8_t j = 0; j < 3; ++j)
+            arr[j] += numbers[i][j];
+        for (uint8_t j = 2; j > 0; --j)
+            if (arr[j] > ten18) {
+                arr[j - 1] += arr[j] / ten18;
+                arr[j] %= ten18;
+            }
     }
-    while (high > ten10)
-        high /= 10;
-    return high;
+    while (arr[0] > ten10)
+        arr[0] /= 10;
+    return arr[0];
 }
 
 PROGRAM_TAIL(p0013)
diff --git a/cplusplus/src/p0015.cpp b/cplusplus/src/p0015.cpp
index 2640221e..21788c6c 100644
--- a/cplusplus/src/p0015.cpp
+++ b/cplusplus/src/p0015.cpp
@@ -21,10 +21,8 @@ How many such routes are there through a 20×20 grid?
 #include "include/macros.hpp"
 #include "include/math.hpp"
 
-#define lattice_paths(height, width) (n_choose_r(height + width, height))
-
 uint64_t EMSCRIPTEN_KEEPALIVE p0015() {
-    return lattice_paths(20, 20);
+    return n_choose_r(40, 20);
 }
 
 PROGRAM_TAIL(p0015)
diff --git a/cplusplus/src/p0017.cpp b/cplusplus/src/p0017.cpp
index 87bb6a2d..92b3f4d1 100644
--- a/cplusplus/src/p0017.cpp
+++ b/cplusplus/src/p0017.cpp
@@ -95,18 +95,14 @@ std::string ToString(uint64_t n) {
 
 uint64_t EMSCRIPTEN_KEEPALIVE p0017() {
     uint64_t answer = 0;
+    std::string filter[2] = {" ", "-"};
+    size_t pos, i;
     for (uint32_t x = 1; x < 1001; x += 1) {
         std::string str = ToString(x);
-        size_t pos = str.find(" ");
-        while (pos != std::string::npos) {
-            str.replace(pos, 1, "");
-            pos = str.find(" ", pos + 1);
-        }
-        pos = str.find("-");
-        while (pos != std::string::npos) {
-            str.replace(pos, 1, "");
-            pos = str.find("-", pos + 1);
-        }
+        for (pos = 0, i = 0; i < 2; i++)
+            while ((pos = str.find(" ", pos)) != std::string::npos)
+                str.replace(pos, 1, "");
+
         answer += str.length();
     }
     return answer;