From 8a55b8a69a7750f251adbffdce688b6b5857d280 Mon Sep 17 00:00:00 2001
From: edwinwalela <edwinwalela@gmail.com>
Date: Wed, 28 Oct 2020 13:18:13 +0300
Subject: [PATCH 1/3] add diagonal difference

---
 Maths/diagonal-difference.c | 87 +++++++++++++++++++++++++++++++++++++
 1 file changed, 87 insertions(+)
 create mode 100644 Maths/diagonal-difference.c

diff --git a/Maths/diagonal-difference.c b/Maths/diagonal-difference.c
new file mode 100644
index 0000000..bebb14f
--- /dev/null
+++ b/Maths/diagonal-difference.c
@@ -0,0 +1,87 @@
+#include <stdio.h>
+#include <stdlib.h>
+/*
+    Print the absolute difference between the sums of the matrix's  two diagonals
+
+    Sample input:
+    3
+    11  2   4
+    4   5   6
+    10  8  -12
+
+    Expected output:
+    15
+
+    Explanation:
+    The first line of input contains a single integer, n , which represents
+    the number of rows and columns in the matrix
+
+    Each of the next (n) lines describes a row, arr[i], and consists of (n) 
+    '/n' separated integers arr[i][j].
+
+*/
+
+int diagonalDifference(int n,int** arr){
+    int primaryDiag[n]; 
+    int secondaryDiag[n];
+
+    // Get integers in primary diagonal
+    for(int i = 0; i < n; i++){
+        primaryDiag[i] = arr[i][i];
+    }
+    int i = 0;
+    int j = n-1;
+
+    // Get integers in secondary diagonal 
+    while(i < n){
+        secondaryDiag[i] = arr[i][j];
+        i++;
+        j--;
+    }
+
+    int mainSum = 0;
+    int subSum = 0;
+
+    // Sum primary diagonal
+    for(int i = 0; i < n; i++){
+        mainSum += primaryDiag[i];
+    }
+
+    // Sum secondary diagonal
+    for(int i = 0; i < n; i++){
+        subSum += secondaryDiag[i];
+    }
+
+    int diff = mainSum - subSum;
+
+    if(diff < 0){ // If negative multiply by -1 to get absolute value
+        diff *= -1 ;
+    }
+
+    return diff;
+}
+
+int main(){
+    int n; // 
+    scanf("%d",&n);
+
+    // Initialize an array of pointers to represent matrix
+    int** matrix = (int**) malloc(n*sizeof(int*));
+    for(int i = 0; i < n; i++){
+        matrix[i] = (int *) malloc(n*sizeof(int*));
+    }
+
+    // Populate array with input
+    for(int i = 0; i < n; i++){
+        for(int k = 0; k < n; k++){
+            scanf("%d",&matrix[i][k]);
+        }
+    }
+
+    int diff = diagonalDifference(n,matrix);
+
+    // Print diff
+    printf("diagonal difference = %d\n",diff);
+
+    return 1;
+}
\ No newline at end of file

From 5cd001febee2a58d8d1b7f8552371fb6e0adc795 Mon Sep 17 00:00:00 2001
From: edwinwalela <edwinwalela@gmail.com>
Date: Wed, 28 Oct 2020 13:18:51 +0300
Subject: [PATCH 2/3] add gitignore

---
 .gitignore | 1 +
 1 file changed, 1 insertion(+)
 create mode 100644 .gitignore

diff --git a/.gitignore b/.gitignore
new file mode 100644
index 0000000..adb36c8
--- /dev/null
+++ b/.gitignore
@@ -0,0 +1 @@
+*.exe
\ No newline at end of file

From 0e2cda88e5e92fa4dbeffa98449907981737f945 Mon Sep 17 00:00:00 2001
From: edwinwalela <edwinwalela@gmail.com>
Date: Wed, 28 Oct 2020 13:39:55 +0300
Subject: [PATCH 3/3] add iterative factorial

---
 Maths/Factorial-iterative.c | 35 +++++++++++++++++++++++++++++++++++
 1 file changed, 35 insertions(+)
 create mode 100644 Maths/Factorial-iterative.c

diff --git a/Maths/Factorial-iterative.c b/Maths/Factorial-iterative.c
new file mode 100644
index 0000000..4856a27
--- /dev/null
+++ b/Maths/Factorial-iterative.c
@@ -0,0 +1,35 @@
+#include <stdio.h>
+#include <stdlib.h>
+
+/*
+    Compute factorial using iteration
+
+    e.g Factorial of 3:
+    3 * 2 * 1;
+*/
+
+int factorial(int n){
+    unsigned long fact = 1;
+    if (n < 0){
+        printf("Factorial of a negative number doesn't exist.");
+        exit(0);
+    }else {
+        for (int i = 1; i <= n; ++i) {
+            fact *= i;
+        }
+        return fact;
+    }
+}
+
+int main() {
+    int n;
+    unsigned long x;
+    
+    printf("Enter an integer: ");
+    scanf("%d", &n);
+    x = factorial(n);
+    printf("Factorial of %d = %lu", n, x);
+    
+
+    return 0;
+}
\ No newline at end of file