Create minimum-genetic-mutation.cpp

Author: kamyu104

C++/minimum-genetic-mutation.cpp

@@ -0,0 +1,40 @@
+// Time:  O(n * b), n is the length of gene string, b is size of bank
+// Space: O(b)
+
+class Solution {
+public:
+    int minMutation(string start, string end, vector<string>& bank) {
+        unordered_map<string, bool> lookup;
+        for (const auto& b : bank) {
+            lookup.emplace(b, false);
+        }
+
+        queue<pair<string, int>> q;
+        q.emplace(start, 0);
+        while (!q.empty()) {
+            string cur;
+            int level;
+            tie(cur, level) = q.front(); q.pop();
+
+            if (cur == end) {
+                return level;
+            }
+
+            for (int i = 0; i < cur.size(); ++i) {
+                auto cur_copy = cur;
+                for (const auto& c : {'A', 'T', 'C', 'G'}) {
+                    if (cur_copy[i] == c) {
+                        continue;
+                    }
+                    cur_copy[i] = c;
+                    if (lookup.count(cur_copy) && lookup[cur_copy] == false) {
+                        q.emplace(cur_copy, level + 1);
+                        lookup[cur_copy] = true;
+                    }
+                }
+            }
+        }
+
+        return -1;
+    }
+};