Create ugly_numbers_ii.cpp

Author: avidLearnerInProgress

ugly_numbers_ii.cpp

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+class Solution {
+public:
+    int nthUglyNumber(int n) {
+        vector<int> ugly(n);
+        ugly[0] = 1; //ugly of first number is 1
+        
+        int i2 = 0, i3 = 0, i5 = 0;
+        int nm2 = 2, nm3 = 3, nm5 = 5;
+        int next_ugly_number = 1;
+        
+        for(int i=1; i<n; i++) {
+            next_ugly_number = min(nm2, min(nm3, nm5));
+            ugly[i] = min(nm2 * ugly[i2], min(nm3 * ugly[i3], nm5 * ugly[i5]));
+            if(ugly[i] == 2 * ugly[i2]) i2++;
+            if(ugly[i] == 3 * ugly[i3]) i3++;
+            if(ugly[i] == 5 * ugly[i5]) i5++;
+        }
+        return ugly[n-1];
+    }
+};