Are two strings anagram?

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/****************************************************************************************** ******************************************************************************************* Chapter 1 Arrays and Strings * Are two strings anagram? By: Hamed Kiani (July 15, 2015) ****************************************************************************************** ******************************************************************************************/ #include "stdafx.h" #include <iostream> #include <cstring> using namespace std; // additional space: O(n), time: O(n) // how about merge sort with time of O(n log n) and no additional space? bool are_anagram(char *s1, char *s2) { // return false if null // return false for strings with different length if (!s1 || !s2) return false; if (strlen(s1) != strlen(s2)) return false; int count[256] = { 0 }; for (int i = 0; s1[i] != '\0'; i++) { count[(int) s1[i]]++; count[(int) s2[i]]--; } for (int i = 0; i < 256; i++) if (count[i] > 0) return false; return true; } int main() { char s1[] = "mai setin tg twostrings !"; char s2[] = "i am testing two strings!"; bool check = are_anagram(s1, s2); if (check) cout << s1 << " and " << s2 << " are angram " << endl; else cout << s1 << " and " << s2 << " are not angram " << endl; return 0; }