Project Euler Solutions Added.

Project Euler/Problem 01/sol1.py

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+'''
+Problem Statement:
+If we list all the natural numbers below 10 that are multiples of 3 or 5,
+we get 3,5,6 and 9. The sum of these multiples is 23.
+Find the sum of all the multiples of 3 or 5 below N.
+'''
+n = int(raw_input().strip())
+sum=0;
+for a in range(3,n):
+    if(a%3==0 or a%5==0):
+        sum+=a
+print sum;

Project Euler/Problem 01/sol2.py

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+'''
+Problem Statement:
+If we list all the natural numbers below 10 that are multiples of 3 or 5,
+we get 3,5,6 and 9. The sum of these multiples is 23.
+Find the sum of all the multiples of 3 or 5 below N.
+'''
+n = int(raw_input().strip())
+sum = 0
+terms = (n-1)/3
+sum+= ((terms)*(6+(terms-1)*3))/2 #sum of an A.P.
+terms = (n-1)/5
+sum+= ((terms)*(10+(terms-1)*5))/2
+terms = (n-1)/15
+sum-= ((terms)*(30+(terms-1)*15))/2
+print sum

Project Euler/Problem 01/sol3.py

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+'''
+Problem Statement:
+If we list all the natural numbers below 10 that are multiples of 3 or 5,
+we get 3,5,6 and 9. The sum of these multiples is 23.
+Find the sum of all the multiples of 3 or 5 below N.
+'''
+'''
+This solution is based on the pattern that the successive numbers in the series follow: 0+3,+2,+1,+3,+1,+2,+3.
+'''
+n = int(raw_input().strip())
+sum=0;
+num=0;
+while(1):
+    num+=3
+    if(num>=n):
+        break
+    sum+=num
+    num+=2
+    if(num>=n):
+        break
+    sum+=num
+    num+=1
+    if(num>=n):
+        break
+    sum+=num
+    num+=3
+    if(num>=n):
+        break
+    sum+=num
+    num+=1
+    if(num>=n):
+        break
+    sum+=num
+    num+=2
+    if(num>=n):
+        break
+    sum+=num
+    num+=3
+    if(num>=n):
+        break
+    sum+=num
+print sum;