面试题3：数组中重复的数字：找出数组中重复的数字

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/*******************************************************************
Copyright(c) 2017, htfeng
All rights reserved.
*******************************************************************/

//==================================================================
// 《剑指Offer——名企面试官精讲典型编程题》代码
//  作者：何海涛
//  C++
//==================================================================

// 面试题3：数组中重复的数字
// 题目1：找出数组中重复的数字

#include<iostream>

using namespace std;

bool duplicate(int numbers[], int length, int* duplicate) {
    if (numbers == 0 || length < 0)
        return false;
    for (int i = 0; i < length; i++) {
        if (numbers[i] < 0 || numbers[i] > length - 1)
            return false;
    }

    for (int i = 0; i < length; i++) {
        while (numbers[i] != i) {
            if (numbers[i] == numbers[numbers[i]]) {
                *duplicate = numbers[i];
                return true;
            }

            int temp = numbers[i];
            numbers[i] = numbers[temp];
            numbers[temp] = temp;
        }
    }
    return false;
}

//=========================test=====================================
// 长度为n的数组里包含一个或多个重复的数字
void test1() {
    int numbers[] = { 2, 3, 1, 0, 2, 5, 3 };
    int length = sizeof(numbers)/sizeof(int);
    int duplication;
    bool result = duplicate(numbers, length, &duplication);
    cout << result << endl;
}

// 数组里不包含重复的数字
void test2() {
    int numbers[] = { 2, 3, 1, 0, 5};
    int length = sizeof(numbers) / sizeof(int);
    int duplication;
    bool result = duplicate(numbers, length, &duplication);
    cout << result << endl;
}

// 无效的输入用例
void test3() {
    int* numbers = nullptr;
    int length = sizeof(numbers) / sizeof(int);
    int duplication;
    bool result = duplicate(numbers, length, &duplication);
    cout << result << endl;
}
int main() {
    test1();
    test2();
    test3();
    system("pause");
    return 0;
}