Develope

AP1403 - WarmUp/src/main/java/Exercises.java

@@ -4,8 +4,13 @@ public class Exercises {
         complete this function to check if the input number is prime or not
      */
     public boolean isPrime(long n) {
-        // todo
-        return false;
+        if (n <= 1)
+            return false;
+        for (int i = 2; i <= (n / 2) ; i++) {
+            if (n % i == 0)  {
+                return  false; }
+        }
+        return true;
     }
 
     /*
@@ -15,7 +20,18 @@ public boolean isPrime(long n) {
         if the input is not a fibonacci number with description above, return -1
      */
     public long fibonacciIndex(long n) {
-        // todo
+     if (n== 0) return 0;
+     if (n == 1) return 1;
+     int a = 0 , b = 1 , c = 1;
+     int res = 1;
+     while (c < n ) {
+         c = a + b;
+         res++;
+         a = b;
+         b = c;
+     }
+     if (c == n) return res;
+
         return -1;
     }
 
@@ -38,8 +54,25 @@ public long fibonacciIndex(long n) {
         the output has to be a two-dimensional array of characters, so don't just print the triangle!
      */
     public char[][] generateTriangle(int n) {
-        // todo
-        return null;
+        if (n == 0) {
+            return new char[0][0];
+        }
+
+        char[][] triangle = new char[n][];
+
+        for (int i = 0; i < n; i++) {
+            triangle[i] = new char[i + 1];
+
+            for (int j = 0; j <= i; j++) {
+                if (j == 0 || j == i || i == n - 1) {
+                    triangle[i][j] = '*';
+                } else {
+                    triangle[i][j] = ' ';
+                }
+            }
+        }
+
+        return triangle;
     }
 
     public static void main(String[] args) {