Update minbin.cpp

minbin.cpp

@@ -0,0 +1,25 @@
+/*
+Goldman Sachs IITD 2018
+
+We are given an array of size N, we can delete a subset b1b2b3...bk from the 
+array if 2^b1 + 2^b2 + …..2^bk = 2^x for non-negative integer x where ^ is the
+power operator. Find the minimum number of steps required to delete the 
+complete array.
+
+0 <= ai <= 1000000
+1 <= N <= 1000000
+
+O(N + log N)
+*/
+int minBin(vector<int> a) {
+	int n = max_element(a.begin(),a.end());
+	vector<int> c(n + 30);
+	for (int ai : a) c[ai]++;
+
+	int ans = 0;
+	for (int i = 0; i < n + 25; i++) {
+		if (c[i] & 1) ans++;
+		c[i + 1] += c[i] >> 1;
+	}
+	return ans;
+}