Create isomorphic-strings.js

lightningtgc · lightningtgc · commit 3cd9f7e708ed · 2015-06-07T01:33:17.000+08:00
diff --git a/leetcode/isomorphic-strings.js b/leetcode/isomorphic-strings.js
@@ -0,0 +1,46 @@
+/*
+* Question: 同构同形字符串
+
+* Given two strings s and t, determine if they are isomorphic.
+
+* Two strings are isomorphic if the characters in s can be replaced to get t.
+
+* All occurrences of a character must be replaced with another character while preserving the order of characters. No two characters may map to the same character but a character may map to itself.
+
+*For example,
+*Given "egg", "add", return true.
+
+*Given "foo", "bar", return false.
+
+*Given "paper", "title", return true.
+
+*Note:
+* You may assume both s and t have the same length.
+*/
+
+
+/**
+ * @param {string} s
+ * @param {string} t
+ * @return {boolean}
+ */
+var isIsomorphic = function(s, t) {
+    
+    var i = s.length - 1;
+    var sMap = {};
+    var tMap = {};
+   
+   for (; 0 <= i; i--) {
+       var source = sMap[t[i]];
+       var target = tMap[s[i]];
+        if (!source && !target){
+            sMap[t[i]] = s[i];
+            tMap[s[i]] = t[i];
+        } else if(source !== s[i] || target !== t[i]) {
+            return false;
+        }
+          
+   }
+    
+    return true;
+}
