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ConstuctArray.cpp
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144 lines (118 loc) · 4.06 KB
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/*******************************************************************
Copyright(c) 2016, Harry He
All rights reserved.
Distributed under the BSD license.
(See accompanying file LICENSE.txt at
https://github.com/zhedahht/CodingInterviewChinese2/blob/master/LICENSE.txt)
*******************************************************************/
//==================================================================
// 《剑指Offer——名企面试官精讲典型编程题》代码
// 作者：何海涛
//==================================================================
// 面试题66：构建乘积数组
// 题目：给定一个数组A[0, 1, …, n-1]，请构建一个数组B[0, 1, …, n-1]，其
// 中B中的元素B[i] =A[0]×A[1]×… ×A[i-1]×A[i+1]×…×A[n-1]。不能使用除法。
#include <cstdio>
#include <vector>
using namespace std;
void BuildProductionArray(const vector<double>& input, vector<double>& output)
{
int length1 = input.size();
int length2 = output.size();
if(length1 == length2 && length2 > 1)
{
output[0] = 1;
for(int i = 1; i < length1; ++i)
{
output[i] = output[i - 1] * input[i - 1];
}
double temp = 1;
for(int i = length1 - 2; i >= 0; --i)
{
temp *= input[i + 1];
output[i] *= temp;
}
}
}
//================= Test Code =================
static bool EqualArrays(const vector<double>& input, const vector<double>& output)
{
int length1 = input.size();
int length2 = output.size();
if(length1 != length2)
return false;
for(int i = 0; i < length1; ++i)
{
if(abs(input[i] - output[i]) > 0.0000001)
return false;
}
return true;
}
static void test(char* testName, const vector<double>& input, vector<double>& output, const vector<double>& expected)
{
printf("%s Begins: ", testName);
BuildProductionArray(input, output);
if(EqualArrays(output, expected))
printf("Passed.\n");
else
printf("FAILED.\n");
}
static void test1()
{
// 输入数组中没有0
double input[] = { 1, 2, 3, 4, 5 };
double output[] = { 0, 0, 0, 0, 0 };
double expected[] = { 120, 60, 40, 30, 24 };
test("Test1", vector<double>(input, input + sizeof(input) / sizeof(double)),
vector<double>(output, output + sizeof(output) / sizeof(double)),
vector<double>(expected, expected + sizeof(expected) / sizeof(double)));
}
static void test2()
{
// 输入数组中有一个0
double input[] = { 1, 2, 0, 4, 5 };
double output[] = { 0, 0, 0, 0, 0 };
double expected[] = { 0, 0, 40, 0, 0 };
test("Test2", vector<double>(input, input + sizeof(input) / sizeof(double)),
vector<double>(output, output + sizeof(output) / sizeof(double)),
vector<double>(expected, expected + sizeof(expected) / sizeof(double)));
}
static void test3()
{
// 输入数组中有两个0
double input[] = { 1, 2, 0, 4, 0 };
double output[] = { 0, 0, 0, 0, 0 };
double expected[] = { 0, 0, 0, 0, 0 };
test("Test3", vector<double>(input, input + sizeof(input) / sizeof(double)),
vector<double>(output, output + sizeof(output) / sizeof(double)),
vector<double>(expected, expected + sizeof(expected) / sizeof(double)));
}
static void test4()
{
// 输入数组中有正、负数
double input[] = { 1, -2, 3, -4, 5 };
double output[] = { 0, 0, 0, 0, 0 };
double expected[] = { 120, -60, 40, -30, 24 };
test("Test4", vector<double>(input, input + sizeof(input) / sizeof(double)),
vector<double>(output, output + sizeof(output) / sizeof(double)),
vector<double>(expected, expected + sizeof(expected) / sizeof(double)));
}
static void test5()
{
// 输入输入中只有两个数字
double input[] = { 1, -2 };
double output[] = { 0, 0 };
double expected[] = { -2, 1 };
test("Test5", vector<double>(input, input + sizeof(input) / sizeof(double)),
vector<double>(output, output + sizeof(output) / sizeof(double)),
vector<double>(expected, expected + sizeof(expected) / sizeof(double)));
}
int main(int argc, char* argv[])
{
test1();
test2();
test3();
test4();
test5();
return 0;
}