Merge pull request #1334 from julienChemillier/patch-21

Add 205 in c language

Author: Ahmad-A0

c/205-Isomorphic-Strings.c

@@ -0,0 +1,35 @@
+/*
+Given two strings s and t, determine if they are isomorphic.
+
+Space: O(1)
+Time: O(n)
+*/
+
+bool isIsomorphic(char * s, char * t){
+    int alphabet_s[256]; // Alphabet of t letters to s
+    int alphabet_t[256]; // Alphabet of s letters to t
+    for (int i=0; i<256; i++){ // Fill alphabets with empty values
+        alphabet_s[i] = -1;
+        alphabet_t[i] = -1;
+    }
+    int i; // To be able to use it outside the loop for
+    for (i=0; s[i]!='\0'; i++) {
+        if (alphabet_t[s[i]]==-1 && alphabet_s[t[i]]==-1) {
+            alphabet_t[s[i]] = t[i];
+            alphabet_s[t[i]] = s[i];
+        } else if (alphabet_t[s[i]]==-1) {
+            if (alphabet_s[t[i]] != s[i]) {
+                return false;
+            }
+            alphabet_t[s[i]] = t[i];
+        }  else if (alphabet_s[t[i]]==-1) {
+            if (alphabet_t[s[i]] != t[i]) {
+                return false;
+            }
+            alphabet_s[t[i]] = s[i];
+        } else if (alphabet_t[s[i]] != t[i] || alphabet_s[t[i]] != s[i]) {
+            return false;
+        }
+    }
+    return t[i]=='\0';
+}