first commit

1.1.cpp

@@ -0,0 +1,53 @@
+#include <iostream>
+#include <cstring>
+using namespace std;
+
+bool isUnique1(string s)
+{
+    bool a[256];
+    memset(a, 0, sizeof(a));
+    int len = s.length();
+    for(int i=0; i<len; ++i)
+    {
+        int v = (int)s[i];
+        if(a[v]) return false;
+        a[v] = true;
+    }
+    return true;
+}
+
+bool isUnique2(string s)
+{
+    int a[8];
+    memset(a, 0, sizeof(a));
+    int len = s.length();
+    for(int i=0; i<len; ++i)
+    {
+        int v = (int)s[i];
+        int idx = v/32, shift=v%32;
+        if(a[idx] & (1<<shift)) return false;
+        a[idx] |= (1<<shift);
+    }
+    return true;
+}
+
+bool isUnique3(string s)
+{
+    int check = 0;
+    int len = s.length();
+    for(int i=0; i<len; ++i)
+    {
+        int v = (int)(s[i]-'a');
+        if(check & (1<<v)) return false;
+        check |= (1<<v);
+    }
+    return true;
+}
+int main()
+{
+    string s1 = "i am hawstein.";
+    string s2 = "abcdefghijklmnopqrstuvwxyz1234567890";
+    cout<<isUnique1(s1)<<" "<<isUnique1(s2)<<endl;
+    cout<<isUnique2(s1)<<" "<<isUnique2(s2)<<endl;
+    return 0;
+}

1.2.cpp

@@ -0,0 +1,43 @@
+#include <iostream>
+#include <cstring>
+using namespace std;
+
+void swap(char &a, char &b)
+{
+    a = a^b;
+    b = a^b;
+    a = a^b;
+}
+
+void reverse2(char *s)
+{
+    int n = strlen(s);
+    for(int i=0; i<n/2; ++i)
+        swap(s[i], s[n-i-1]);
+}
+
+void reverse(char *s)
+{
+    char *end = s;
+    char tmp;
+    if(s)
+    {
+        while(*end)
+            ++end;
+        --end;
+        while(s < end)
+        {
+            tmp = *s;
+            *s++ = *end;
+            *end-- = tmp;
+        }
+    }
+}
+int main()
+{
+    char s[] = "1234567890";
+    reverse2(s);
+    cout<<s<<endl;
+    return 0;
+
+}

1.3.cpp

@@ -0,0 +1,118 @@
+#include <iostream>
+#include <cstring>
+using namespace std;
+
+string removeDuplicate1(string s)
+{
+    int check = 0;
+    int len = s.length();
+    if(len < 2) return s;
+    string str = "";
+    for(int i=0; i<len; ++i)
+    {
+        int v = (int)(s[i]-'a');
+        if((check & (1<<v)) == 0)
+        {
+            str += s[i];
+            check |= (1<<v);
+        }
+    }
+    return str;
+}
+
+string removeDuplicate2(string s)
+{
+    int len = s.length();
+    if(len < 2) return s;
+    string str = "";
+    for(int i=0; i<len; ++i)
+    {
+        if(s[i] != '\0')
+        {
+            str += s[i];
+            for(int j=i+1; j<len; ++j)
+                if(s[j]==s[i])
+                    s[j] = '\0';
+        }
+    }
+    return str;
+}
+
+void removeDuplicate3(char s[])
+{
+    int len = strlen(s);
+    if(len < 2) return;
+    int p = 0;
+    for(int i=0; i<len; ++i)
+    {
+        if(s[i] != '\0')
+        {
+            s[p++] = s[i];
+            for(int j=i+1; j<len; ++j)
+                if(s[j]==s[i])
+                    s[j] = '\0';
+        }
+    }
+    s[p] = '\0';
+}
+
+void removeDuplicate4(char s[])
+{
+    int len = strlen(s);
+    if(len < 2) return;
+    bool c[256];
+    memset(c, 0, sizeof(c));
+    int p = 0;
+    for(int i=0; i<len; ++i)
+    {
+        if(!c[s[i]])
+        {
+            s[p++] = s[i];
+            c[s[i]] = true;
+        }
+    }
+    s[p] = '\0';    
+}
+
+void removeDuplicate5(char s[])
+{
+    int len = strlen(s);
+    if(len < 2) return;
+    int check = 0, p = 0;
+    for(int i=0; i<len; ++i)
+    {
+        int v = (int)(s[i]-'a');
+        if((check & (1<<v))==0)
+        {
+            s[p++] = s[i];
+            check |= (1<<v);
+        }
+    }
+    s[p] = '\0';
+}
+int main()
+{
+    string s1 = "abcde";
+    string s2 = "aaabbb";
+    string s3 = "";
+    string s4 = "abababc";
+    string s5 = "ccccc";
+    cout<<removeDuplicate1(s1)<<" "<<removeDuplicate2(s1)<<endl;
+    cout<<removeDuplicate1(s2)<<" "<<removeDuplicate2(s2)<<endl;
+    cout<<removeDuplicate1(s3)<<" "<<removeDuplicate2(s3)<<endl;
+    cout<<removeDuplicate1(s4)<<" "<<removeDuplicate2(s4)<<endl;
+    cout<<removeDuplicate1(s5)<<" "<<removeDuplicate2(s5)<<endl;
+    char ss1[] = "abcde";
+    char ss2[] = "aaabbb";
+    char ss3[] = "";
+    char ss4[] = "abababc";
+    char ss5[] = "ccccc";
+    removeDuplicate5(ss1);
+    removeDuplicate5(ss2);
+    removeDuplicate5(ss3);
+    removeDuplicate5(ss4);
+    removeDuplicate5(ss5);
+    cout<<ss1<<" "<<ss2<<" "<<ss3<<" "<<ss4<<" "<<ss5<<endl;
+    //cout<<removeDuplicate1(s6)<<" "<<removeDuplicate2(s6)<<endl;
+    return 0;
+}

1.4.cpp

@@ -0,0 +1,36 @@
+#include <iostream>
+#include <cstring>
+#include <algorithm>
+using namespace std;
+
+bool isAnagram1(string s, string t)
+{
+    sort(&s[0], &s[0]+s.length());
+    sort(&t[0], &t[0]+t.length());
+    if(s == t) return true;
+    else return false;
+}
+bool isAnagram(string s, string t)
+{
+    if(s=="" || t=="") return false;
+    if(s.length() != t.length()) return false;
+    int len = s.length();
+    int c[256];
+    memset(c, 0, sizeof(c));
+    for(int i=0; i<len; ++i)
+        ++c[(int)s[i]];
+    for(int i=0; i<len; ++i)
+        --c[(int)t[i]];
+    for(int i=0; i<256; ++i)
+        if(c[i] != 0)
+            return false;
+    return true;
+}
+int main()
+{
+    string s = "aaabbb";
+    string t = "ababab";
+    //cout<<isAnagram(s, t)<<endl;
+    cout<<isAnagram1(s, t)<<endl;
+    return 0;
+}

1.5.cpp

@@ -0,0 +1,72 @@
+#include <iostream>
+#include <cstring>
+using namespace std;
+
+char* replace1(char *c)
+{
+    int len = strlen(c);
+    if(len == 0) return NULL;
+    int cnt = 0;
+    for(int i=0; i<len; ++i)
+    {
+        if(c[i] == ' ')
+            ++cnt;
+    }
+    char *cc = new char[len+2*cnt];
+    int p = 0;
+    for(int i=0; i<len; ++i)
+    {
+        if(c[i] == ' ')
+        {
+            cc[p] = '%';
+            cc[p+1] = '2';
+            cc[p+2] = '0';
+            p += 3;
+        }
+        else
+        {
+            cc[p] = c[i];
+            ++p;
+        }
+    }
+    cc[p] = '\0';
+    return cc;
+}
+
+void replace2(char *c)
+{
+    int len = strlen(c);
+    if(len == 0) return;
+    int cnt = 0;
+    for(int i=0; i<len; ++i)
+    {
+        if(c[i] == ' ')
+            ++cnt;
+    }
+    int p = len + 2*cnt;
+    c[p] = '\0';//the space must be allocated first.
+    --p;
+    for(int i=len-1; i>=0; --i)
+    {
+        if(c[i] == ' ')
+        {
+            c[p] = '0';
+            c[p-1] = '2';
+            c[p-2] = '%';
+            p -= 3;
+        }
+        else
+        {
+            c[p] = c[i];
+            --p;
+        }
+    }
+}
+int main()
+{
+    char c[] = "i am hawstein.";
+    cout<<replace1(c)<<endl;
+    //replace2(c);
+    cout<<c<<endl;
+    return 0;
+}

1.6.cpp

@@ -0,0 +1,41 @@
+#include <iostream>
+using namespace std;
+
+void swap(int &a, int &b)
+{
+    int t = a;
+    a = b;
+    b = t;
+}
+void transpose(int a[][4], int n)
+{
+    for(int i=0; i<n; ++i)
+        for(int j=i+1; j<n; ++j)
+            swap(a[i][j], a[j][i]);
+    for(int i=0; i<n/2; ++i)
+        for(int j=0; j<n; ++j)
+            swap(a[i][j], a[n-1-i][j]);
+}
+int main()
+{
+    int a[4][4] = {
+        {1, 2, 3, 4},
+        {5, 6, 7, 8},
+        {9, 10, 11, 12},
+        {13, 14, 15, 16}
+    };
+    for(int i=0; i<4; ++i)
+    {
+        for(int j=0; j<4; ++j)
+            cout<<a[i][j]<<" ";
+        cout<<endl;
+    }
+    transpose(a, 4);
+    for(int i=0; i<4; ++i)
+    {
+        for(int j=0; j<4; ++j)
+            cout<<a[i][j]<<" ";
+        cout<<endl;
+    }
+    return 0;
+}