diff --git a/a074.cpp b/a074.cpp
new file mode 100644
index 0000000..ac80f61
--- /dev/null
+++ b/a074.cpp
@@ -0,0 +1,68 @@
+#include <iostream>
+#include <cmath>
+#include <chrono>
+
+using namespace std;
+int factorials[10] = {1, 1, 2, 6, 24, 120, 720, 5040, 40320, 362880};
+int cycleLength[2200000];
+
+inline int digitFactorial(int a)
+{
+    int sum = 0;
+    while (a > 0)
+    {
+        sum += factorials[a % 10];
+        a /= 10;
+    }
+    return sum;
+}
+
+int cycle(int n, int depth)
+{
+    if (depth > 1000)
+        cout << "{ \"depth\": " << depth << ", \"n\": " << n << " }" << endl;
+    int cl = cycleLength[n];
+    if (cl < 0)
+        return -cl;
+    if (cl == 0)
+    {
+        cl = cycle(digitFactorial(n), depth+1);
+        cycleLength[n] = cl;
+    }
+    return cl+1;
+}
+
+int main()
+{
+    auto start = chrono::system_clock::now();
+
+    cycleLength[0] = -1;
+    cycleLength[1] = -1;
+    cycleLength[2] = -1;
+    cycleLength[169] = -3;
+    cycleLength[145] = -1;
+    cycleLength[871] = -2;
+    cycleLength[872] = -2;
+    cycleLength[1454] = -3;
+    cycleLength[40585] = -3;
+    cycleLength[45361] = -2;
+    cycleLength[45362] = -2;
+    cycleLength[363601] = -3;
+
+    cout << "cycle length 69: " << cycle(69,0) << endl;
+
+    int sixties = 0;
+    for (int n = 0; n < 1000000; n++)
+    {
+        if (cycle(n,0) == 60)
+            sixties++;
+    }
+
+    auto end = std::chrono::system_clock::now();
+
+    std::chrono::duration<double> elapsed_seconds = end - start;
+    cout << "cycles took: " << elapsed_seconds.count() << endl;
+
+    cout << "numbers with 60 cycles: " << sixties;
+    return 0;
+}
diff --git a/a075.cpp b/a075.cpp
new file mode 100644
index 0000000..c5a8d10
--- /dev/null
+++ b/a075.cpp
@@ -0,0 +1,75 @@
+#include <iostream>
+#include <cmath>
+#include <chrono>
+#define lmax 1500000
+
+using namespace std;
+typedef unsigned char byte;
+
+inline int isqrt(int n) {
+    return (int)sqrt((float)n);
+}
+
+template<class T>
+inline T gcd(T a, T b) {
+    while(b) {
+        auto t = a % b;
+        a = b;
+        b = t;
+    }
+    return a;
+}
+
+int main() {
+    byte arr[lmax+1];
+    auto start = chrono::system_clock::now();
+
+    for (int i = 0; i <= lmax; i++)
+        arr[i] = 0;
+
+    for (int length = 12; length <= lmax; length += 2)
+    for (int m = isqrt(length)/2+1; m <= isqrt(length/2); m++) {
+        if (length % (2*m) == 0) 
+            {
+                int n = length / (2*m) - m;
+                if (n>0 && n < m && n%2!= m%2 && gcd(m,n) == 1)
+                arr[length]++;
+                }
+    }
+
+    auto middle = std::chrono::system_clock::now();
+
+    std::chrono::duration<double> elapsed_seconds = middle-start;
+    cout << "generating primitives took: " << elapsed_seconds.count() << endl;
+
+
+    for (int length = lmax; length >= 0; length--) {
+        int sqrtlen = isqrt(length);
+        for (int prev_length = 2; prev_length <= sqrtlen; prev_length++)
+            if (length % prev_length == 0) {
+                arr[length] += arr[prev_length];
+                arr[length] += arr[length/prev_length];
+                if (arr[length] > 1)
+                    break;
+            }
+    }
+    auto end = std::chrono::system_clock::now();
+
+    elapsed_seconds = end-middle;
+    cout << "adding multiples took: " << elapsed_seconds.count() << endl;
+
+
+    int singles = 0;
+
+    for (int i = 0; i <= lmax; i++)
+        if (arr[i] == 1)
+            singles++;
+
+    for (int i = 0; i <= 60; i++)
+        if (arr[i] == 1)
+            cout << i << ", ";
+    cout << endl;
+
+    cout << singles;
+    return 0;
+}
\ No newline at end of file
diff --git a/a076.cpp b/a076.cpp
new file mode 100644
index 0000000..fd10bb1
--- /dev/null
+++ b/a076.cpp
@@ -0,0 +1,35 @@
+#include <iostream>
+#include <cmath>
+#include <chrono>
+
+using namespace std;
+
+int main() {
+    int m[101][101];
+    auto start = chrono::high_resolution_clock::now();
+
+    for (int n = 1; n <= 100; n++)
+        m[1][n] = 1;
+
+    for (int t = 1; t <= 100; t++)
+        m[t][1] = 1;
+
+    for (int t = 2; t <= 100; t++)
+    for (int n = 2; n <= 100; n++) {
+        if (n >  t)
+            m[t][n] = m[t][n-1];
+        if (n == t)
+            m[t][n] = m[t][n-1]+1;
+        if (n <  t)
+            m[t][n] = m[t][n-1]+m[t-n][n];
+    }
+
+    auto end = std::chrono::high_resolution_clock::now();
+
+    std::chrono::duration<double> elapsed_seconds = end-start;
+    cout << "problem took: " << elapsed_seconds.count() << endl;
+
+    cout << m[100][99];
+
+    return 0;
+}
\ No newline at end of file
diff --git a/a091.cpp b/a091.cpp
new file mode 100644
index 0000000..f437d1b
--- /dev/null
+++ b/a091.cpp
@@ -0,0 +1,43 @@
+#include <iostream>
+#include <cmath>
+#include <chrono>
+#define sq 3
+
+using namespace std;
+typedef unsigned char byte;
+
+template<class T>
+inline T gcd(T a, T b) {
+    while(b) {
+        auto t = a % b;
+        a = b;
+        b = t;
+    }
+    return a;
+}
+
+int main() {
+    auto start = chrono::system_clock::now();
+
+    //triangles for which either (x1,y1) == (0,0)
+    //or x1==0,y1!=0 or x1!=0,y1==0
+    long count = 3*sq*sq;
+
+    for (int vx = 1; vx <= sq; vx++)
+    for (int vy = 1; vy <= sq; vy++) {
+        int dx = -vy/gcd(vx,vy);
+        int dy = vx/gcd(vx,vy);
+        for (int d = 1; vx+dx*d >= 0 && vy+dy*d <= sq; d++)
+            count++;
+        for (int d = -1; vx+dx*d <= sq && vy+dy*d >= 0; d--)
+            count++;
+    }
+
+    auto end = std::chrono::system_clock::now();
+
+    std::chrono::duration<double> elapsed_seconds = end-start;
+    cout << "solving took: " << elapsed_seconds.count() << endl;
+
+    cout << "triangles: " << count;
+    return 0;
+}
diff --git a/a094.cpp b/a094.cpp
new file mode 100644
index 0000000..4c97ca3
--- /dev/null
+++ b/a094.cpp
@@ -0,0 +1,46 @@
+#include <iostream>
+#include <cmath>
+#include <chrono>
+#define pmax 1000000000ll
+
+using namespace std;
+typedef long long var;
+
+template<typename T> inline bool isSquare(T val) {
+    T root = (T)sqrt((double)val);
+    return root*root == val;
+}
+
+int main() {
+    auto start = chrono::system_clock::now();
+
+    var perimeterSum = 0;
+    var count = 0;
+
+    for (var equalSide = 3; equalSide <= pmax/3+1; equalSide += 2) {
+        var otherSide = equalSide-1;
+        var s = equalSide + otherSide/2;
+        if (isSquare(s*(s-otherSide)) && 2*s <= pmax) {
+            perimeterSum += 2*s;
+            count++;
+            cout << "(" << equalSide << "," << equalSide << "," << otherSide << ")" << endl;
+        }
+
+        otherSide = equalSide+1;
+        s = equalSide + otherSide/2;
+        if (isSquare(s*(s-otherSide)) && 2*s <= pmax) {
+            perimeterSum += 2*s;
+            count++;
+            cout << "(" << equalSide << "," << equalSide << "," << otherSide << ")" << endl;
+        }
+    }
+
+    auto end = std::chrono::system_clock::now();
+
+    std::chrono::duration<double> elapsed_seconds = end-start;
+    cout << "solving took: " << elapsed_seconds.count() << endl;
+    cout << "perimeter count: " << count << endl;
+
+    cout << "perimeter sum: " << perimeterSum;
+    return 0;
+}
diff --git a/a206.cpp b/a206.cpp
new file mode 100644
index 0000000..f004464
--- /dev/null
+++ b/a206.cpp
@@ -0,0 +1,33 @@
+#include <iostream>
+#include <cmath>
+#include <chrono>
+#define lmax 1500000
+
+using namespace std;
+typedef unsigned char byte;
+
+inline int isqrt(int n) {
+    return (int)sqrt((float)n);
+}
+
+inline uint64_t isqrt(uint64_t n) {
+    return (uint64_t)sqrt((double)n);
+}
+
+int main() {
+    auto start = chrono::system_clock::now();
+
+    for (uint64_t i = isqrt(10203040506070809ull); i <= isqrt(19293949596979899ull); i++) {
+        uint64_t square = i*i;
+
+        if (square % 10ull == 9 && (square/100ull) % 10ull == 8 && (square/10000ull) % 10ull == 7 && (square/1000000ull) % 10ull == 6 && (square/100000000ull) % 10ull == 5 && (square/10000000000ull) % 10ull == 4 && (square/1000000000000ull) % 10ull == 3 && (square/100000000000000ull) % 10ull == 2 && (square/10000000000000000ull) == 1)
+            cout << "found " << i << " ^2 = " << square << endl;
+    }
+
+    auto end = std::chrono::system_clock::now();
+
+    std::chrono::duration<double> elapsed_seconds = end-start;
+    cout << "iterating took: " << elapsed_seconds.count() << endl;
+
+    return 0;
+}
\ No newline at end of file
diff --git a/a233.cpp b/a233.cpp
new file mode 100644
index 0000000..f9e575c
--- /dev/null
+++ b/a233.cpp
@@ -0,0 +1,87 @@
+#include <iostream>
+#include <vector>
+#include <cmath>
+#include <chrono>
+typedef long long int Int;
+
+using namespace std;
+
+vector<Int> primes;
+
+void generatePrimes() {
+    primes.push_back(2);
+    primes.push_back(3);
+    for (int i = 5; i < 1000000; i += 2) {
+        bool isPrime = true;
+        for (auto p : primes) {
+            if ((int)p*(int)p > i)
+                break;
+            if (i % (int)p == 0) {
+                isPrime = false;
+                break;
+            }
+        }
+        if (isPrime)
+            primes.push_back((Int)i);
+    }
+}
+
+bool check420LatticePoints(Int n) {
+    int latticePoints = 1;
+
+    for (auto p : primes) {
+        if (p*p > n)
+            p = n;
+
+        int multiplicity = 0;
+
+        while (n % p == 0) {
+            multiplicity++;
+            n /= p;
+        }
+
+        if (multiplicity > 0 && p % 4 == 1) {
+            latticePoints *= 2*multiplicity+1;
+
+            if (latticePoints == 105)
+                return true;
+
+            if (105 % latticePoints != 0)
+                return false;
+        }
+
+        if (n==1)
+            return false;
+    }
+    return false;
+}
+
+int main() {
+    Int max;
+    cout << "N = ";
+    cin >> max;
+
+    auto start = chrono::system_clock::now();
+
+    generatePrimes();
+
+    auto middle = std::chrono::system_clock::now();
+
+    std::chrono::duration<double> elapsed_seconds = middle-start;
+    cout << "generating primes took: " << elapsed_seconds.count() << endl;
+
+    Int count = 0, sum = 0;
+    for (Int n = 10; n < max; n++) {
+        if (check420LatticePoints(n)) {
+            sum += n;
+            count++;
+        }
+    }
+    auto end = std::chrono::system_clock::now();
+
+    elapsed_seconds = end-middle;
+    cout << "finding 420s took: " << elapsed_seconds.count() << endl << endl;
+
+    cout << "sum: " << sum << ", total: " << count;
+    return 0;
+}