From 2f2e94424904011b9c96ec405f3781de0fce4a40 Mon Sep 17 00:00:00 2001
From: Sombit Bose <sombit.bose15@gmail.com>
Date: Wed, 30 Sep 2020 20:23:07 +0530
Subject: [PATCH 1/3] Create Problem12.java

Added solution for problem 12 of Project Euler
---
 ProjectEuler/Problem12.java | 63 +++++++++++++++++++++++++++++++++++++
 1 file changed, 63 insertions(+)
 create mode 100644 ProjectEuler/Problem12.java

diff --git a/ProjectEuler/Problem12.java b/ProjectEuler/Problem12.java
new file mode 100644
index 000000000..d85721d76
--- /dev/null
+++ b/ProjectEuler/Problem12.java
@@ -0,0 +1,63 @@
+/*
+    The sequence of triangle numbers is generated by adding the natural numbers. So the 7th triangle number would be 1 + 2 + 3 + 4 + 5 + 6 + 7 = 28.
+    The first ten terms would be:
+
+    1, 3, 6, 10, 15, 21, 28, 36, 45, 55, ...
+
+    Let us list the factors of the first seven triangle numbers:
+
+     1: 1
+     3: 1,3
+     6: 1,2,3,6
+    10: 1,2,5,10
+    15: 1,3,5,15
+    21: 1,3,7,21
+    28: 1,2,4,7,14,28
+    We can see that 28 is the first triangle number to have over five divisors.
+
+    What is the value of the first triangle number to have over five hundred divisors?
+*/
+
+public class Problem_12_Highly_Divisible_Triangular_Number {
+
+    /* returns the nth triangle number; that is, the sum of all the natural numbers less than, or equal to, n */
+    public static int triangleNumber(int n) {
+        int sum = 0;
+        for (int i = 0; i <= n; i++)
+            sum += i;
+        return sum;
+    }
+
+    public static void main(String[] args) {
+
+        long start = System.currentTimeMillis(); // start the stopwatch
+        
+        int j = 0; // j represents the jth triangle number
+        int n = 0; // n represents the triangle number corresponding to j
+        int numberOfDivisors = 0; // number of divisors for triangle number n
+        
+        while (numberOfDivisors <= 500) {
+
+            // resets numberOfDivisors because it's now checking a new triangle number
+            // and also sets n to be the next triangle number
+            numberOfDivisors = 0;
+            j++;
+            n = triangleNumber(j);
+            
+            // for every number from 1 to the square root of this triangle number,
+            // count the number of divisors
+            for (int i = 1; i <= Math.sqrt(n); i++)
+                if (n % i == 0)
+                    numberOfDivisors++;
+            
+            // 1 to the square root of the number holds exactly half of the divisors
+            // so multiply it by 2 to include the other corresponding half
+            numberOfDivisors *= 2;
+        }
+        
+        long finish = System.currentTimeMillis(); // stop the stopwatch
+        
+        System.out.println(n);
+        System.out.println("Time taken: " + (finish - start) + " milliseconds");
+    }
+}

From 064d941722674cd023d3e8e5f59823fbc0d691b3 Mon Sep 17 00:00:00 2001
From: Sombit Bose <sombit.bose15@gmail.com>
Date: Tue, 6 Oct 2020 07:34:52 +0530
Subject: [PATCH 2/3] Update Problem12.java

---
 ProjectEuler/Problem12.java | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/ProjectEuler/Problem12.java b/ProjectEuler/Problem12.java
index d85721d76..72e1b5b71 100644
--- a/ProjectEuler/Problem12.java
+++ b/ProjectEuler/Problem12.java
@@ -18,7 +18,7 @@
     What is the value of the first triangle number to have over five hundred divisors?
 */
 
-public class Problem_12_Highly_Divisible_Triangular_Number {
+public class Problem_12 {
 
     /* returns the nth triangle number; that is, the sum of all the natural numbers less than, or equal to, n */
     public static int triangleNumber(int n) {

From 8ad87ce9d3c09b8d2e3382e58b6e3aa0651c8e06 Mon Sep 17 00:00:00 2001
From: shellhub <shellhub.me@gmail.com>
Date: Tue, 6 Oct 2020 14:58:38 +0800
Subject: [PATCH 3/3] reformat

---
 ProjectEuler/Problem12.java | 69 +++++++++++++++++++------------------
 1 file changed, 36 insertions(+), 33 deletions(-)

diff --git a/ProjectEuler/Problem12.java b/ProjectEuler/Problem12.java
index 72e1b5b71..89ea3e0ac 100644
--- a/ProjectEuler/Problem12.java
+++ b/ProjectEuler/Problem12.java
@@ -1,24 +1,34 @@
-/*
-    The sequence of triangle numbers is generated by adding the natural numbers. So the 7th triangle number would be 1 + 2 + 3 + 4 + 5 + 6 + 7 = 28.
-    The first ten terms would be:
+package ProjectEuler;
+/**
+ * The sequence of triangle numbers is generated by adding the natural numbers.
+ * So the 7th triangle number would be 1 + 2 + 3 + 4 + 5 + 6 + 7 = 28.
+ * The first ten terms would be:
+ * <p>
+ * 1, 3, 6, 10, 15, 21, 28, 36, 45, 55, ...
+ * <p>
+ * Let us list the factors of the first seven triangle numbers:
+ * <p>
+ * 1: 1
+ * 3: 1,3
+ * 6: 1,2,3,6
+ * 10: 1,2,5,10
+ * 15: 1,3,5,15
+ * 21: 1,3,7,21
+ * 28: 1,2,4,7,14,28
+ * We can see that 28 is the first triangle number to have over five divisors.
+ * <p>
+ * What is the value of the first triangle number to have over five hundred divisors?
+ * <p>
+ * link: https://projecteuler.net/problem=12
+ */
+public class Problem12 {
 
-    1, 3, 6, 10, 15, 21, 28, 36, 45, 55, ...
-
-    Let us list the factors of the first seven triangle numbers:
-
-     1: 1
-     3: 1,3
-     6: 1,2,3,6
-    10: 1,2,5,10
-    15: 1,3,5,15
-    21: 1,3,7,21
-    28: 1,2,4,7,14,28
-    We can see that 28 is the first triangle number to have over five divisors.
-
-    What is the value of the first triangle number to have over five hundred divisors?
-*/
-
-public class Problem_12 {
+    /**
+     * Driver Code
+     */
+    public static void main(String[] args) {
+        assert solution1(500) == 76576500;
+    }
 
     /* returns the nth triangle number; that is, the sum of all the natural numbers less than, or equal to, n */
     public static int triangleNumber(int n) {
@@ -28,36 +38,29 @@ public class Problem_12 {
         return sum;
     }
 
-    public static void main(String[] args) {
-
-        long start = System.currentTimeMillis(); // start the stopwatch
-        
+    public static int solution1(int number) {
         int j = 0; // j represents the jth triangle number
         int n = 0; // n represents the triangle number corresponding to j
         int numberOfDivisors = 0; // number of divisors for triangle number n
-        
-        while (numberOfDivisors <= 500) {
+
+        while (numberOfDivisors <= number) {
 
             // resets numberOfDivisors because it's now checking a new triangle number
             // and also sets n to be the next triangle number
             numberOfDivisors = 0;
             j++;
             n = triangleNumber(j);
-            
+
             // for every number from 1 to the square root of this triangle number,
             // count the number of divisors
             for (int i = 1; i <= Math.sqrt(n); i++)
                 if (n % i == 0)
                     numberOfDivisors++;
-            
+
             // 1 to the square root of the number holds exactly half of the divisors
             // so multiply it by 2 to include the other corresponding half
             numberOfDivisors *= 2;
         }
-        
-        long finish = System.currentTimeMillis(); // stop the stopwatch
-        
-        System.out.println(n);
-        System.out.println("Time taken: " + (finish - start) + " milliseconds");
+        return n;
     }
 }