CareerCup_1_1

Implement an algorithm to determine if a string has all unique characters. What if you cannot use additional data structures?

/*Implement an algorithm to determine if a string has all unique characters. What if you cannot use additional data structures?*/// 256个char字母const int CHAR_NUM = 256;/* * Using Hash to determine that a char is unique*/bool IsStringUniqueChar(char str[]);/* * Using bitmap*/bool IsStringUniqueChar2(char str[]);// unsigned char的长度为8const int CHAR_LENGTH = 8;// Setbit #define SETBIT(arr, num) \(arr[num / CHAR_LENGTH] |= (1 << (num % CHAR_LENGTH)))// ClearBit#define CLRBIT(arr, num) \(arr[num / CHAR_LENGTH] &= (~(((unsigned char)1) << (num % CHAR_LENGTH))))// GetBit#define GETBIT(arr, num) \((arr[num / CHAR_LENGTH] >> (num % CHAR_LENGTH)) & 1)// ByteNum#define BYTENUM(num) \((num % CHAR_LENGTH == 0) ? (num / CHAR_LENGTH) : (num / CHAR_LENGTH + 1))void TestBitMap();/* * brute force*/bool IsStringUniqueChar3(char str[]);/* * sort, then iterator the str*/bool IsStringUniqueChar4(char str[]);void TestUniqueCharacer();

#include <iostream>#include <cassert>#include <algorithm>#include "1_1_UniqueCharacter.h"using namespace std;void TestUniqueCharacer(){char str[256];strcpy(str, "acdefghibbjklmnopqrstuvwxyzz");cout << (IsStringUniqueChar4(str) ? "True" : "False") << endl;strcpy(str, "abcdefghijklmnopqrstuvwxyz");cout << (IsStringUniqueChar4(str) ? "True" : "False") << endl;strcpy(str, "abcdefggijklmnopprstuvwxyz");cout << (IsStringUniqueChar4(str) ? "True" : "False") << endl;}void TestBitMap(){int num1 = 31;int byteNum = BYTENUM(num1);assert(byteNum == 4);unsigned char *bitMap = new unsigned char[byteNum];memset(bitMap, 0, sizeof(bitMap));SETBIT(bitMap, 0);assert(GETBIT(bitMap, 0) == 1);CLRBIT(bitMap, 0);assert(GETBIT(bitMap, 0) == 0);SETBIT(bitMap, 3);assert(GETBIT(bitMap, 3) == 1);CLRBIT(bitMap, 3);assert(GETBIT(bitMap, 3) == 0);SETBIT(bitMap, 7);assert(GETBIT(bitMap, 7) == 1);CLRBIT(bitMap, 7);assert(GETBIT(bitMap, 7) == 0);SETBIT(bitMap, 8);assert(GETBIT(bitMap, 8) == 1);CLRBIT(bitMap, 8);assert(GETBIT(bitMap, 8) == 0);SETBIT(bitMap, 15);assert(GETBIT(bitMap, 15) == 1);CLRBIT(bitMap, 15);assert(GETBIT(bitMap, 15) == 0);delete []bitMap;}bool IsStringUniqueChar(char str[]){if (str == NULL){return false;}bool bHashArr[CHAR_NUM] = {0};size_t len = strlen(str);for (size_t i = 0; i < len; ++i){unsigned char ch = static_cast<unsigned char>(str[i]);if (bHashArr[ch]){return false;}bHashArr[ch] = true;}return true;}bool IsStringUniqueChar2(char str[]){if (str == NULL){return false;}size_t len = strlen(str);int byteNum = BYTENUM(CHAR_NUM);unsigned char *bitMap = new unsigned char[byteNum];if (bitMap == NULL){cerr << "Allocate memory failed" << endl;exit(-1);}memset(bitMap, 0, sizeof(unsigned char) * byteNum);bool ans = true;for (size_t i = 0; i < len; ++i){unsigned char ch = static_cast<unsigned char>(str[i]);if (GETBIT(bitMap, ch) == 1){ans = false;break;}SETBIT(bitMap, ch);}delete []bitMap;return ans;}bool IsStringUniqueChar3(char str[]){if (str == NULL){return false;}size_t len = strlen(str);for (size_t i = 0; i < len; ++i){char ch = str[i];for (size_t j = i + 1; j < len; ++j){if (ch == str[j]){return false;}}}return true;}bool IsStringUniqueChar4(char str[]){if (str == NULL){return false;}size_t len = strlen(str);sort(str, str + len);for (size_t i = 1; i < len; ++i){if (str[i - 1] == str[i]){return false;}}return true;}