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Data Structures and Algorithms → Introduction to DSA 32

The output of: int a=INT_MIN; cout<<(a<0?"negative":"positive");
negative
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What is the output: cout<<numeric_limits<int>::max();
All correct
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The output of: double x=1.0/3.0; cout<<fixed<<setprecision(15)<<x;
0.333333333333333
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What is epsilon comparison for floating point?
abs(a-b)<epsilon (for small epsilon)
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The output of: cout<<(0.1+0.2==0.3);
0
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Which is the output: double a=0.1+0.2; cout<<fixed<<setprecision(20)<<a;
0.30000000000000004440
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The output of: int n=5; string s(n,*); cout<<s;
*****
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The output of: string s="Hello"; s.insert(5," World"); cout<<s;
Hello World
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The output of: string s="Hello World"; s.replace(6,5,"C++"); cout<<s;
Hello C++
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What does string::npos equal?
-1 as size_t (maximum size_t value)
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The output of: string s="hello"; for(auto &c:s) c=toupper(c); cout<<s;
HELLO
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The output of: string s="12345"; int n=stoi(s); cout<<n*2;
24690
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The output of: int n=42; string s=to_string(n); cout<<s.length();
2
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The output of: vector<string> v={"Hello","World"}; string result=accumulate(v.begin(),v.end(),string("")); cout<<result;
HelloWorld
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The output of: auto f=function<int(int)>([](int n){return n*n;}); cout<<f(7);
49
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The output of: map<string,int> freq; string words[]={"a","b","a","c","b","a"}; for(auto w:words)freq[w]++; cout<<freq["a"]<<freq["b"]<<freq["c"];
321
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The output of: vector<pair<int,int>> v={{3,1},{1,3},{2,2}}; sort(v.begin(),v.end()); cout<<v[0].first<<v[0].second;
13
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The output of: priority_queue<pair<int,int>> pq; pq.push({1,2}); pq.push({3,1}); pq.push({2,3}); cout<<pq.top().first;
3
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The output of: auto it=find(begin({5,3,8,1,9}),end({5,3,8,1,9}),8); cout<<*it;
8
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What is the time complexity of std::sort?
O(n log n) average
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What is the space complexity of quicksort (average)?
O(log n) recursion stack
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Which sort is best for nearly sorted arrays?
Insertion Sort
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Counting sort is not a comparison sort and runs in:
O(n + k) where k is range of values
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Bucket sort is efficient when input is:
Uniformly distributed in a known range
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Tim sort (used in Python and Java) combines:
Insertion sort for small runs + merge sort
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The output of: int arr[]={5,2,8,1,9}; int n=5; for(int i=0;i<n-1;i++) for(int j=0;j<n-i-1;j++) if(arr[j]>arr[j+1]) swap(arr[j],arr[j+1]); cout<<arr[0];
1
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What is the maximum comparisons in binary search for n=1024 elements?
11
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Interpolation search works best when:
Data is uniformly distributed (better than binary search)
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Exponential search is useful when:
Array is sorted and size is unknown (infinite/very large)
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Jump search works by:
Jumping ahead by sqrt(n) steps then linear search back
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The output of: int a[]={1,1,2,2,3}; cout<<distance(a,unique(a,a+5));
3
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What is Big Theta of the best sort algorithm for general data?
O(n log n)
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Data Structures and Algorithms → Sorting Algorithms 5

What is the space complexity of merge sort?
O(n)
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What is the space complexity of heap sort?
O(1) in-place
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Radix sort time complexity for n numbers with d digits:
O(d*n)
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Shell sort is a generalization of:
Insertion sort (with gap sequences)
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The output of: int arr[]={64,34,25,12,22,11,90}; // selection sort: for(int i=0;i<6;i++){int m=i; for(int j=i+1;j<7;j++) if(arr[j]<arr[m]) m=j; swap(arr[i],arr[m]);} cout<<arr[0];
11
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Data Structures and Algorithms → Linked List 1

Which sort is best for linked lists?
Merge Sort
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Data Structures and Algorithms → Arrays 2

Binary search on sorted array {1,3,5,7,9,11,13}: how many comparisons to find 7?
3
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Ternary search divides array into:
Three parts (finds max/min of unimodal function)
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