uglynumbers

dynamic_programming/Uglynumbers.cpp

@@ -0,0 +1,48 @@
+
+// C++ program to find n'th Ugly number 
+# include<bits/stdc++.h> 
+using namespace std; 
+
+/* Function to get the nth ugly number*/
+unsigned getNthUglyNo(unsigned n) 
+{ 
+    unsigned ugly[n]; // To store ugly numbers 
+    unsigned i2 = 0, i3 = 0, i5 = 0; 
+    unsigned next_multiple_of_2 = 2; 
+    unsigned next_multiple_of_3 = 3; 
+    unsigned next_multiple_of_5 = 5; 
+    unsigned next_ugly_no = 1; 
+
+    ugly[0] = 1; 
+    for (int i=1; i<n; i++) 
+    { 
+       next_ugly_no = min(next_multiple_of_2, 
+                           min(next_multiple_of_3, 
+                               next_multiple_of_5)); 
+       ugly[i] = next_ugly_no; 
+       if (next_ugly_no == next_multiple_of_2) 
+       { 
+           i2 = i2+1; 
+           next_multiple_of_2 = ugly[i2]*2; 
+       } 
+       if (next_ugly_no == next_multiple_of_3) 
+       { 
+           i3 = i3+1; 
+           next_multiple_of_3 = ugly[i3]*3; 
+       } 
+       if (next_ugly_no == next_multiple_of_5) 
+       { 
+           i5 = i5+1; 
+           next_multiple_of_5 = ugly[i5]*5; 
+       } 
+    } /*End of for loop (i=1; i<n; i++) */
+    return next_ugly_no; 
+} 
+
+/* Driver program to test above functions */
+int main() 
+{ 
+    int n = 150; 
+    cout << getNthUglyNo(n); 
+    return 0; 
+}