checkpermutation in o(1)

rishavranjan943 · rishavranjan943 · commit 60077083b7b7 · 2023-10-03T02:49:48.000+05:30
diff --git a/1-Array-And-String/CheckPermutation.cpp b/1-Array-And-String/CheckPermutation.cpp
@@ -18,18 +18,14 @@ bool checkPermutation( string string1, string string2 ) {
   if( string1.length() != string2.length() ) {
     return false;
   }
-  int charMap[128] = {0};
-  for( int i=0; i < string1.length(); i++ ) {
-    charMap[ string1[ i ] ]++;
+  int xorValue=0;
+  for(char ch : string1){
+    xorValue^=ch;
   }
-
-  for( int i=0; i < string2.length(); i++ ) {
-    if( charMap[ string2[ i ] ] == 0 ) {
-      return false;
-    }
-    charMap[ string2[ i ] ]--;
+  for(char ch : string2){
+    xorValue^=ch;
   }
-  return true;
+  return xorValue==0;
 }
 
 bool checkPermutationUsingSorting( string input1, string input2 ) {

Original file line number	Diff line number	Diff line change
`@@ -18,18 +18,14 @@ bool checkPermutation( string string1, string string2 ) {`
`18`	`18`	`if( string1.length() != string2.length() ) {`
`19`	`19`	`return false;`
`20`	`20`	`}`
`21`		`- int charMap[128] = {0};`
`22`		`- for( int i=0; i < string1.length(); i++ ) {`
`23`		`- charMap[ string1[ i ] ]++;`
	`21`	`+ int xorValue=0;`
	`22`	`+ for(char ch : string1){`
	`23`	`+ xorValue^=ch;`
`24`	`24`	`}`
`25`		`-`
`26`		`- for( int i=0; i < string2.length(); i++ ) {`
`27`		`- if( charMap[ string2[ i ] ] == 0 ) {`
`28`		`- return false;`
`29`		`- }`
`30`		`- charMap[ string2[ i ] ]--;`
	`25`	`+ for(char ch : string2){`
	`26`	`+ xorValue^=ch;`
`31`	`27`	`}`
`32`		`- return true;`
	`28`	`+ return xorValue==0;`
`33`	`29`	`}`
`34`	`30`
`35`	`31`	`bool checkPermutationUsingSorting( string input1, string input2 ) {`