Update word-pattern.cpp

kamyu104 · kamyu104 · commit 513e8d61e8f2 · 2015-10-06T00:05:47.000+08:00
diff --git a/C++/word-pattern.cpp b/C++/word-pattern.cpp
@@ -1,5 +1,5 @@
 // Time:  O(n)
-// Space: O(c), c is unique count of pattern and words
+// Space: O(c), c is count of pattern
 
 class Solution {
 public:
@@ -16,21 +16,20 @@ class Solution {
 
         unordered_map<string, char> word2pattern;
         unordered_map<char, string> pattern2word;
-        for (int i = 0, idx = 0, space_idx = 0;
-             i < pattern.size();
-             ++i, idx = space_idx + 1) {
-                 
-            space_idx = str.find(" ", idx) != string::npos ?
-                        str.find(" ", idx) :
-                        str.length();
-            string word = str.substr(idx, space_idx - idx);
-            if (word2pattern[word] == 0 &&
-                pattern2word[pattern[i]] == "") { 
-                word2pattern[word] = pattern[i]; 
-                pattern2word[pattern[i]] = word; 
-            } else if (word2pattern[word] != pattern[i]) {
+        int i = 0, j = 0;
+        for (const auto& p : pattern) {
+            j = str.find(" ", i);
+            if (j == string::npos) {
+                j = str.length();
+            }
+            string word = str.substr(i, j - i);
+            if (!word2pattern.count(word) && !pattern2word.count(p)) { 
+                word2pattern[word] = p; 
+                pattern2word[p] = word; 
+            } else if (word2pattern[word] != p) {
                 return false;
             }
+            i = j + 1;
         }
         return true;
     }
