diff --git a/Maths/NthUglyNumber.java b/Maths/NthUglyNumber.java new file mode 100644 index 000000000..cd7674e90 --- /dev/null +++ b/Maths/NthUglyNumber.java @@ -0,0 +1,59 @@ +// Ugly numbers are numbers whose only prime factors are 2, 3 or 5. The sequence 1, 2, 3, 4, 5, 6, 8, 9, 10, 12, 15, … shows the first 11 ugly numbers. +// By convention, 1 is included. +// A program to find the nth Ugly number + +// Algorithm : +// Initialize three-pointers two, three, and five pointing to zero. +// Take 3 variables nm2, nm3, and nm5 to keep track of next multiple of 2,3 and 5. +// Make an array of size n to store the ugly numbers with 1 at 0th index. +// Initialize a variable next which stores the value of the last element in the array. +// Run a loop n-1 times and perform steps 6,7 and 8. +// Update the values of nm2, nm3, nm5 as ugly[two]*2, ugly[three]*3, ugly[5]*5 respectively. +// Select the minimum value from nm2, nm3, and nm5 and increment the pointer related to it. +// Store the minimum value in variable next and array. +// Return next. + + + +package Maths; +import java.util.*; +class NthUglyNumber { + /* Function to get the nth ugly number*/ + public long getNthUglyNo(int n) { + long[] ugly = new long[n]; + int two=0, three=0, five=0; + long nm2=2, nm3=3, nm5=5; + long next = 1; + + ugly[0] = 1; + + for(int i=1; i