JZ-C-42-Plus

剑指offer第四十二题-拓展：左旋转字符串：左旋转操作是把字符串前面的若干个字符转移到字符串的尾部，如输入"abcdefg"和数字2，左旋转2位后为："cdefgab"

//============================================================================
// Name        : JZ-C-42-Plus.cpp
// Author      : Laughing_Lz
// Version     :
// Copyright   : All Right Reserved
// Description : 左旋转字符串：左旋转操作是把字符串前面的若干个字符转移到字符串的尾部，如输入"abcdefg"和数字2，左旋转2位后为："cdefgab"
//============================================================================

#include <iostream>
#include <stdio.h>
#include "StringUtil.h"
#include <string.h>
using namespace std;

char* LeftRotateString(char* pStr, int n) {
    if (pStr != NULL) {
        int nLength = static_cast<int>(strlen(pStr));
        if (nLength > 0 && n > 0 && n < nLength) {
            char* pFirstStart = pStr;
            char* pFirstEnd = pStr + n - 1;
            char* pSecondStart = pStr + n;
            char* pSecondEnd = pStr + nLength - 1;
            // 翻转字符串的前面n个字符
            Reverse(pFirstStart, pFirstEnd);
            // 翻转字符串的后面部分
            Reverse(pSecondStart, pSecondEnd);
            // 翻转整个字符串
            Reverse(pFirstStart, pSecondEnd);
        }
    }

    return pStr;
}

// ====================测试代码====================
void Test(char* testName, char* input, int num, char* expectedResult) {
    if (testName != NULL)
        printf("%s begins: ", testName);

    char* result = LeftRotateString(input, num);

    if ((input == NULL && expectedResult == NULL)
            || (input != NULL && strcmp(result, expectedResult) == 0))
        printf("Passed.

");
    else
        printf("Failed.

");
}

// 功能测试
void Test1() {
    char input[] = "abcdefg";
    char expected[] = "cdefgab";

    Test("Test1", input, 2, expected);
}

// 边界值测试
void Test2() {
    char input[] = "abcdefg";
    char expected[] = "bcdefga";

    Test("Test2", input, 1, expected);
}

// 边界值测试
void Test3() {
    char input[] = "abcdefg";
    char expected[] = "gabcdef";

    Test("Test3", input, 6, expected);
}

// 鲁棒性测试
void Test4() {
    Test("Test4", NULL, 6, NULL);
}

// 鲁棒性测试
void Test5() {
    char input[] = "abcdefg";
    char expected[] = "abcdefg";

    Test("Test5", input, 0, expected);
}

// 鲁棒性测试
void Test6() {
    char input[] = "abcdefg";
    char expected[] = "abcdefg";

    Test("Test6", input, 7, expected);
}

int main(int argc, char** argv) {
    Test1();
    Test2();
    Test3();
    Test4();
    Test5();
    Test6();

    return 0;
}