Sort in difference. This data is very useful for the students Mini
sort(machines.begin(), machines.end(), [](const pair<int, int>& a, const pair<int, int>& b) {
return (a.second - a.first) > (b.second - b.first);});
Input = {(6,7), (3,9), (8,6)}
Output = {(3,9),(6,7),(8,6)}
Sort vector of pairs by second element ascending
vector<pair<int,int>> v = {{1, 3}, {2, 2}, {3, 1}};
sort(v.begin(), v.end(), [](const pair<int,int>& a, const pair<int,int>& b) {
return a.second < b.second;
});
Input:
[(1,3), (2,2), (3,1)]
Output:
[(3,1), (2,2), (1,3)]
Sort vector of pairs by first ascending, then second descending
vector<pair<int,int>> v = {{1, 2}, {1, 3}, {2, 1}};
sort(v.begin(), v.end(), [](const pair<int,int>& a, const pair<int,int>& b) {
if (a.first != b.first)
return a.first < b.first;
return a.second > b.second;
});
Input:
[(1,2), (1,3), (2,1)]
Output:
[(1,3), (1,2), (2,1)]
Sort vector of integers by absolute value descending
vector<int> v = {-10, 5, -3, 8};
sort(v.begin(), v.end(), [](int a, int b) {
return abs(a) > abs(b);
});
Input:
[-10, 5, -3, 8]
Output:
[-10, 8, 5, -3]
Filter a vector to remove even numbers
vector<int> v = {1, 2, 3, 4, 5};
v.erase(remove_if(v.begin(), v.end(), [](int x) {
return x % 2 == 0;
}), v.end());
Input:
[1, 2, 3, 4, 5]
Output:
[1, 3, 5]
Square each element in vector
vector<int> v = {1, 2, 3};
transform(v.begin(), v.end(), v.begin(), [](int x) {
return x * x;
});
Input:
[1, 2, 3]
Output:
[1, 4, 9]
Sort strings by length ascending
vector<string> v = {"apple", "dog", "banana"};
sort(v.begin(), v.end(), [](const string& a, const string& b) {
return a.size() < b.size();
});
Input:
["apple", "dog", "banana"]
Output:
["dog", "apple", "banana"]
Min heap of pairs by second element
auto cmp = [](const pair<int,int>& a, const pair<int,int>& b) {
return a.second > b.second;
};
priority_queue<pair<int,int>, vector<pair<int,int>>, decltype(cmp)> pq(cmp);
pq.push({1, 20});
pq.push({2, 10});
pq.push({3, 30});
while (!pq.empty()) {
cout << "(" << pq.top().first << "," << pq.top().second << ") ";
pq.pop();
}
Input:
Pairs pushed: (1,20), (2,10), (3,30)
Output:
(2,10) (1,20) (3,30)
Sort points by distance from origin ascending
vector<pair<int,int>> points = {{1,2}, {3,4}, {0,1}};
sort(points.begin(), points.end(), [](const pair<int,int>& a, const pair<int,int>& b) {
return (a.first*a.first + a.second*a.second) < (b.first*b.first + b.second*b.second);
});
Input:
[(1,2), (3,4), (0,1)]
Output:
[(0,1), (1,2), (3,4)]
Sort strings ignoring case
vector<string> v = {"Apple", "banana", "apricot"};
sort(v.begin(), v.end(), [](const string& a, const string& b) {
string la = a, lb = b;
transform(la.begin(), la.end(), la.begin(), ::tolower);
transform(lb.begin(), lb.end(), lb.begin(), ::tolower);
return la < lb;
});
Input:
["Apple", "banana", "apricot"]
Output:
["Apple", "apricot", "banana"]
