add solution of problem 313: super ugly number

Author: ppulse

SuperUglyNumber313/README.md

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+Write a program to find the n<sup>th</sup> super ugly number.
+
+Super ugly numbers are positive numbers whose all prime factors are in the given prime list `primes` of size `k`. For example, `[1, 2, 4, 7, 8, 13, 14, 16, 19, 26, 28, 32]` is the sequence of the first 12 super ugly numbers given `primes` = `[2, 7, 13, 19]` of size 4.
+
+#####Note:
+(1) `1` is a super ugly number for any given `primes`.
+(2) The given numbers in `primes` are in ascending order.
+(3) 0 < `k` ≤ 100, 0 < `n` ≤ 10<sup>6</sup>, 0 < `primes[i]` < 1000.

SuperUglyNumber313/Solution.java

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+public class Solution {
+    public int nthSuperUglyNumber(int n, int[] primes) {
+        if (n <= 0 || primes == null || primes.length == 0)
+            return 0;
+        
+        int k = primes.length;
+        int[] multiplesIdx = new int[k];
+        int[] product = new int[k];
+        for (int i = 0; i < k; i++) {
+            multiplesIdx[i] = 1;
+            product[i] = primes[i];
+        }
+        
+        int[] result = new int[n + 1];
+        result[1] = 1;
+        
+        for (int i = 2; i <= n; i++) {
+            int minValue = product[0];
+            for (int j = 1; j < k; j++) {
+                int value = product[j];
+                if (value < minValue)
+                    minValue = value;
+            }
+            
+            result[i] = minValue;
+            
+            for (int j = 0; j < k; j++) {
+                if (product[j] == minValue) {
+                    multiplesIdx[j]++;
+                    product[j] = primes[j] * result[multiplesIdx[j]];
+                }
+            }
+        }
+        
+        return result[n];
+    }
+}