Data Structures

Chapter 1 | Arrays and Strings

1.1  Implement an algorithm to determine if a string has all unique characters What if you can not use additional data structures?

#include <stdio.h>#include <string>#include <iostream>#include <time.h>#include <math.h>using namespace std;bool isUniqString(string s){    bool hit[256] = {0};    for (int i = 0; i < s.size(); i++)    {        int val = s[i];        if (hit[val])        {            return false;        }        hit[val] = true;    }    return true;}bool isUniqString2(string s){    long hit = 0;    for (int i = 0; i < s.size(); i++)    {        int val = s[i] - 'a';        if ((hit & (1 << val)) > 0)        {            return false;        }        hit |= (1 << val);    }    return true;}int main(void){    clock_t start;    clock_t end;    float  duration;    start = clock();    string words[2] = {"adck", "aabb"};    for (int i = 0; i < 2; i++)    {        printf("function 1%s : %d \n", words[i].c_str(), isUniqString(words[i]));        printf("function 2%s : %d \n", words[i].c_str(), isUniqString2(words[i]));    }    end = clock() - start;    printf("It took me %d clocks %f seconds \n", end, ((float)end)/CLOCKS_PER_SEC);}

1.2  Write code to reverse a C-Style String (C-String means that “abcd” is represented as five characters, including the null character )

#include <iostream>#include <string>#include <stdio.h>#include <time.h>#include <math.h>#include <algorithm>//c++ sting reversevoid stl_reverse(std::string& str){    reverse(str.begin(), str.end());}void bad_reverse(std::string& str){    std::string tmp(str);    std::string::size_type ix = str.size() - 1;    for (std::string::size_type i = 0; i < str.size(); i++)    {        str[i] = tmp[ix--];    }}void good_reverse(std::string& str){    size_t first;    size_t last;    first = 0;    last = str.length() -1;    while (first < last)    {        std::swap(str[first++], str[last--]);    }}void reverse(std::string& str){    char tmp;    size_t first;    size_t last;    first = 0;    last = str.length() - 1;    while (first < last)    {        tmp = str[first];        str[first] = str[last];        str[last] = tmp;        first++;        last--;    }}//c char* reversevoid bad_reverse(char* str){    char* tmp = new char[strlen(str)];    strcpy(tmp, str);        size_t ix = strlen(str) - 1;    for (size_t i = 0; i < strlen(str); i++)    {        str[i] = tmp[ix--];    }        delete[] tmp;}void good_reverse(char* str){    char tmp;    size_t start;    size_t end;    start = 0;    end = strlen(str) - 1;    while (start < end)    {        tmp = str[start];         str[start] = str[end];        str[end] = tmp;        start++;        end--;    }}int main(void){    using namespace std;    clock_t start, end;    std::string str = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ";    start = clock();    for (int i = 0 ; i != 10000001 ; i++)    {        bad_reverse(str);         }    end = clock() - start;    cout << str << endl;    printf("bad reverse took me %d ticks %f seconds \n", end, ((float)end)/CLOCKS_PER_SEC);    start = clock();    for (int i = 0 ; i != 10000001 ; i++)    {        stl_reverse(str);         }    end = clock() - start;    cout << str << endl;    printf("stl reverse took me %d ticks %f seconds \n", end, ((float)end)/CLOCKS_PER_SEC);    start = clock();    for (int i = 0 ; i != 10000001 ; i++)    {        good_reverse(str);         }    end = clock() - start;    cout << str << endl;    printf("good reverse took me %d ticks %f seconds \n", end, ((float)end)/CLOCKS_PER_SEC);    start = clock();    for (int i = 0 ; i != 10000001 ; i++)    {        reverse(str);         }    end = clock() - start;    cout << str << endl;    printf("reverse took me %d ticks %f seconds \n", end, ((float)end)/CLOCKS_PER_SEC);    char cs[] = "0123456789abcdefghijklmnopqrstuvwxyz";    start = clock();    for (int i = 0 ; i != 10000001 ; i++)    {        bad_reverse(cs);    }    end = clock() - start;    cout << cs << endl;    printf("reverse took me %d ticks %f seconds \n", end, ((float)end)/CLOCKS_PER_SEC);    start = clock();    for (int i = 0 ; i != 10000001 ; i++)    {        good_reverse(cs);    }    end = clock() - start;    cout << cs << endl;    printf("reverse took me %d ticks %f seconds \n", end, ((float)end)/CLOCKS_PER_SEC);}

1.3  Design an algorithm and write code to remove the duplicate characters in a string without using any additional buffer NOTE: One or two additional variables are fine An extra copy of the array is not.FOLLOW UP Write the test cases for this method

#include <iostream>#include <string>#include <time.h>#include <algorithm>#include <math.h>//use char[] description the char of strstd::string removeDuplicate(std::string str){    int size;    int loop;    int pointer;        size = str.length();    if(size < 2)    {        return "";    }    char hit[256] = {0};    loop = 0;    pointer = 0;        while (pointer < size)    {        int val = str[pointer];        if (hit[val] != '\0')        {            pointer++;            continue;        }        hit[val] = '1';        str[loop] = str[pointer];        loop++;        pointer++;    }    return std::string(str.c_str(), loop);}//use long bit description the char of strstd::string removeDuplicate2(std::string str){    int size;    long hit;    int loop;    int pointer;        size = str.length();    if(size < 2)    {        return "";    }    hit = 0;    loop = 0;    pointer = 0;        while (pointer < size)    {        long val = str[pointer];        if ((hit & (1<< val)) > 0)        {            pointer++;            continue;        }        hit |= 1 << val;        str[loop] = str[pointer];        loop++;        pointer++;    }    return std::string(str.c_str(), loop);}int main(){    std::string str = "fdffdfdfdfdfdfdfdfd909";        std::string rt1 = removeDuplicate(str);    std::cout<<"rt1 is: "<<rt1<<std::endl;    std::string rt2 = removeDuplicate2(str);    std::cout<<"rt2 is: "<<rt2<<std::endl;}

Test Cases:
1   String does not contain any duplicates, e g : abcd
2   String contains all duplicates, e g : aaaa
3   Null string
4   String with all continuous duplicates, e g : aaabbb

5   String with non-contiguous duplicate, e g : abababa

1.4  Write a method to decide if two strings are anagrams or not

#include <iostream>#include <string>#include <time.h>#include <algorithm>#include <math.h>#include <vector>bool anagram(std::string s, std::string d){    int s_size = s.size();    int d_size = d.size();        if (s_size != d_size)    {        return false;    }        int count[256] = {0};    int num_uniq_chars = 0;    int num_complete_chars = 0;        for (int i = 0; i < s_size; i++)    {        int val = s[i];        if(0 == count[val])        {            num_uniq_chars++;        }        count[val]++;    }        for (int i = 0; i < d_size; i++)    {        int val = d[i];        if(0 == count[val])        {            return false;        }                count[val]--;        if (0 == count[val])        {            num_complete_chars++;        }    }        if (num_complete_chars == num_uniq_chars)    {        return true;    }        return false;    } int main(){    using namespace std;    vector<pair<string, string> > pairs;    pairs.push_back(std::make_pair("apple", "papel"));    pairs.push_back(std::make_pair("carrot", "tarroc"));    pairs.push_back(std::make_pair("hello", "llloh"));        string strs[3][2] = {{"apple", "papel"}, {"carrot", "tarroc"}, {"hello", "llloh"}};            for (int i = 0; i < sizeof(strs)/sizeof(strs[0]); i++)    {        bool ret = anagram(strs[i][0], strs[i][1]);        std::cout<<strs[i][0]<<"   "<<strs[i][1]<<"rt is: "<<ret<<std::endl;    }        std::vector<pair<string, string> >::iterator pos;    for (pos = pairs.begin(); pos != pairs.end(); pos++)    {        bool ret = anagram(pos->first, pos->second);        std::cout<<pos->first<<"   "<<pos->second<<"rt is: "<<ret<<std::endl;    }}

1.6 Given an image represented by an NxN matrix, where each pixel in the image is 4 bytes, write a method to rotate the image by 90 degrees Can you do this in place?、

#include <iostream>#include <stdio.h>#include <math.h>#include <algorithm>#include <time.h>#define MARTIX_SIZE 9int rotate(int (*martix)[MARTIX_SIZE], int n){     if ( NULL == martix)     {         return -1;     }          for (int layer = 0; layer < n/2; layer++)     {         int first = layer;         int last = n - layer -1;                  for (int i = first; i < last; i++)         {             int offset = i - first;             int restore = martix[first][i];                          //left   -> top             martix[first][i] = martix[last - offset][first]; //bottom -> left             martix[last - offset][first] = martix[last][last - offset]; //right  -> bottom             martix[last][last - offset] = martix[i][last]; //top    -> right martix[i][last] = restore;         }     }     return 0;}int main(){    int martix[MARTIX_SIZE][MARTIX_SIZE];    for (int i = 0; i < MARTIX_SIZE; i++)    {        for (int j = 0; j < MARTIX_SIZE; j++)        {            martix[i][j] = (i+1)*10 + j;            printf("%d    ", martix[i][j]);        }        printf("\n");    }        rotate(martix, MARTIX_SIZE);      printf("After rotate! \n");    for (int i = 0; i < MARTIX_SIZE; i++)    {        for (int j = 0; j < MARTIX_SIZE; j++)        {            printf("%d    ", martix[i][j]);        }        printf("\n");    }        return 0;}

1.8 Given two strings, s1 and s2, write code to check if s2 is a rotation (i e , “waterbottle” is a rotation of “erbottlewat”)

#include <iostream>#include <stdio.h>#include <math.h>#include <algorithm>#include <time.h>#include <string>//c++ style//identified s2 is a substring of s2 or ontbool isSubStr(std::string s1, std::string s2){    size_t pos = s1.find(s2);        return pos != std::string::npos;}//identified s2 is a rotation of s1 or notbool isRotation(std::string s1, std::string s2){   size_t length1 = s1.length();   size_t length2 = s2.length();   if (length1 != length2)   {       return false;   }         std::string combine = s2 + s2;      return isSubStr(combine, s1);}//c stylechar* myStrstr(const char* s1, const char* s2){     if (NULL == s1 || s2 == NULL)     {         return NULL;     }     const char* t = s2;     const char* s = s1;     for (; '\0' != *s1; s1++)     {         for (t = s2, s = s1; '\0' != *t && *t == *s; s++, t++);                  if ('\0' == *t)         {             return (char*)s1;         }     }          return NULL;}char* myStrcat(char* s, const char* append){    char* save = s;      for (; '\0' != *s; s++);    while ((*s++ = *append++) != '\0');    return save;   }char* myStrcopy(char* dest, const char* source){     if (NULL == dest || NULL == source)     {            return NULL;     }     char* addr = dest;     while ((*dest++ = *source++) != '\0');          return addr;}//identified s2 is a substring of s1 or ontbool c_isSubStr(const char* s1, const char* s2){    char* pointer = myStrstr(s1, s2);        return NULL != pointer;}//identified s2 is a rotation of s1 or notbool c_isRotation(const char* s1, const char* s2){   size_t length1 = strlen(s1);   size_t length2 = strlen(s2);   if (length1 != length2)   {       return false;   }         char* combine = new char[strlen(s2)*2];    myStrcopy(combine, s2);    combine = myStrcat(combine, s2);      return c_isSubStr(combine, s1);}int main(){    clock_t start;    clock_t end;    bool a = false;    bool b = false;    bool c = false;        std::string array[][2] =  {{"apple", "ploap"}, {"waterbottle", "erbottlewat"}, {"camera", "macera"}};        start = clock();    for (int i = 0; i < 1000000; i++)    {        a = isRotation(array[0][0], array[0][1]);        b = isRotation(array[1][0], array[1][1]);        c = isRotation(array[2][0], array[2][1]);    }    end = clock() - start;    printf("%s, %s, %d \n", array[0][0].c_str(), array[0][1].c_str(), a);    printf("%s, %s, %d \n", array[1][0].c_str(), array[1][1].c_str(), b);    printf("c++ style: It took %d clocks %f seconds\n", end, ((float)end)/CLOCKS_PER_SEC);                start = clock();    for (int i = 0; i < 1000000; i++)    {        a = c_isRotation(array[0][0].c_str(), array[0][1].c_str());        b = c_isRotation(array[1][0].c_str(), array[1][1].c_str());        c = c_isRotation(array[2][0].c_str(), array[2][1].c_str());    }    end = clock() - start;    printf("%s, %s, %d \n", array[0][0].c_str(), array[0][1].c_str(), a);    printf("%s, %s, %d \n", array[1][0].c_str(), array[1][1].c_str(), b);    printf("c style: It took %d clocks %f seconds\n", end, ((float)end)/CLOCKS_PER_SEC);    return 0;}

Chapter2

1.1
1.2