Data Structures and Algorithm Analysis in C++ | 4th edition
by Mark A. Weiss
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, Table of Content
Chapter 1 Programming: A General Overview
Chapter 2 Algorithm Analysis
Chapter 3 Lists, Stacks, and Queues
Chapter 4 Trees
Chapter 5 Hashing
Chapter 6 Priority Queues (Heaps)
Chapter 7 Sorting
Chapter 8 The Disjoint Sets Class
Chapter 9 Graph Algorithms
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Chapter 10 Algorithm Design Techniques
Chapter 11 Amortized Analysis
Chapter 12 Advanced Data Structures and Implementation
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CHAPTER 1
Introduction
1.1
/*
Exercise 1.1 All Chapters Included
Selection of integers with k = N/2
select1 => sorting and selecting
select2 => keeping top k
*/ All Answers Included
#include <iostream>
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#include <ctime>
#include <cmath>
#include <vector>
#include <algorithm>
using namespace std;
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void sort(vector<int> & vec)
{ // bubble sort ascending
bool sorted = false;
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while (!sorted)
{
sorted = true;
for (auto i = 1; i < vec.size(); i++)
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{
if (vec[i-1]> vec[i])
{
swap(vec[i],vec[i-1]);
sorted = false;
}
}
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}
}
void sortDec(vector<int> & vec)
{ // bubble sort descending
bool sorted = false;
while (!sorted)
{
sorted = true;
for (auto i = 1; i < vec.size(); i++)
{
if (vec[i-1]< vec[i])
{
swap(vec[i],vec[i-1]);
sorted = false;
}
}
}
}
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int select1(vector<int> nums)
{
int k = (nums.size()+1)/2;
sort(nums);
return nums[k];
}
int select2(const vector<int> &nums)
{
int k = nums.size()/2;
vector<int> topK(nums.begin(), nums.begin() + k);
sortDec(topK);
for (auto i = k; i < nums.size(); i++)
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{
if (nums[i] > topK[k-1])
{
for (auto j = k-2; j >=0 ; j--)
if (nums[i] < topK[j])
{topK[j+1] = nums[i]; break;}
else
topK[j+1] = topK[j];
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if (topK[0] < nums[i])
topK[0] = nums[i];
}
}
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return topK[k-1];
}
int main()
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{
vector<int> nums;
int selected;
time_t start, end;
srand(time(NULL));
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for (auto numInts = 1000; numInts<=10000; numInts+=1000)
// sizes 1,000, 2,000, 3,000, ...10,000
{
nums.resize(numInts);
start = time(NULL);
for (auto i = 0; i < 10; i++) // run 10 times
{
for (auto j = 0; j < numInts; j++)
nums[j] = rand()%(2*numInts);
selected = select1(nums); // or selected = select2(nums);
}
end = time(NULL);
cout<<numInts<<"\t"<<difftime(end,start)<<endl;
}
return 0;
}
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