Update check-if-a-string-can-break-another-string.cpp

Author: kamyu104

C++/check-if-a-string-can-break-another-string.cpp

@@ -1,7 +1,38 @@
-// Time:  O(nlogn)
+// Time:  O(n)
 // Space: O(1)
 
 class Solution {
+public:
+    bool checkIfCanBreak(string s1, string s2) {
+        const auto& count1 = counter(s1), &count2 = counter(s2);
+        return isBreak(count1, count2) || isBreak(count2, count1);
+    }
+
+private:
+    bool isBreak(const vector<int>& count1, const const vector<int>& count2) {
+        int curr1 = 0, curr2 = 0;
+        for (int c = 0; c < 26; ++c) {
+            curr1 += count1[c];
+            curr2 += count2[c];
+            if (curr1 < curr2) {
+                return false;
+            }
+        }
+        return true;
+    }
+    
+    vector<int> counter(const string& word) {
+        vector<int> count(26);
+        for (const auto& c : word) {
+            ++count[c - 'a'];
+        }
+        return count;
+    }
+};
+
+// Time:  O(nlogn)
+// Space: O(1)
+class Solution2 {
 public:
     bool checkIfCanBreak(string s1, string s2) {
         sort(begin(s1), end(s1)), sort(begin(s2), end(s2));
@@ -10,20 +41,20 @@ class Solution {
             if (s1[i] < s2[i]) {
                 flag1 = false;
             }
-			if (s2[i] < s1[i]) {
+            if (s2[i] < s1[i]) {
                 flag2 = false;
             }
             if (!flag1 && !flag2) {
                 return false;
             }
         }
-		return true;
+        return true;
     }
 };
 
 // Time:  O(nlogn)
 // Space: O(1)
-class Solution2 {
+class Solution3 {
 public:
     bool checkIfCanBreak(string s1, string s2) {
         sort(begin(s1), end(s1)), sort(begin(s2), end(s2));