codefun/String_Shift.cpp at master · whodewho/codefun · GitHub

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
#include <iostream>
#include <string>
#include <assert.h>
using namespace std;

string operator<<(string s, size_t n)
{
    size_t length = s.size();
    if(length==0)return s;
    n=n%length;
    if(n==0)return s;

    size_t i=0;
    size_t j=length-1;
    while(i<j)
    {
       swap(s[i], s[j]);
       i++;
       j--;
    }

    i=0;
    j=n-1;
    while(i<j)
    {
        swap(s[i], s[j]);
        i++;
        j--;
    }

    i=n;
    j=length-1;
    while(i<j)
    {
        swap(s[i], s[j]);
        i++;
        j--;
    }
    return s;
}

void testLeftShift_EmptyString()
{
    string s("");
    assert((s<<2)=="");
}

void testLeftShift_ShiftGreatThanLength()
{
    string s("ab");
    assert((s<<3)=="ba");
}

void testLeftShift_ShiftEqualLength()
{
    string s("ab");
    assert((s<<2)=="ab");
}

void testLeftShift_ShiftZero()
{
    string s("ab");
    assert((s<<0)=="ab");
}

void testLeftShift_Normal()
{
    string s("Microsoft");
    assert((s<<2)=="ftMicroso");
}

int main()
{
    testLeftShift_EmptyString();
    testLeftShift_ShiftGreatThanLength();
    testLeftShift_ShiftEqualLength();
    testLeftShift_ShiftZero();
    testLeftShift_Normal();
   return 0;
}