Question

SML Complete the following programs.

1. Write a function listify that takes a list
and returns a list of lists
where each element of first list
becoming its own single-element list

(Fill in the code here)

fun main() = let
val lst = (explode "rad");
in print (PolyML.makestring ( listify lst )) end;

2. Write a function splitlist that takes a list
of pairs and returns a pair of lists
that has the firsts of the pairs in one list
and the seconds of the pairs in the other list

(Fill in the code here)

fun main() = let
val lst = [("a","b"),("c","d"),("e","f")];
in print (PolyML.makestring ( splitlist lst )) end;

3. Write a function sumPairs that takes a list
of pairs of ints and returns a list
of the sum of each pair

(Fill in the code here)

fun main() = let
val lst = [(0,1),(1,0),(10,10)];
in print (PolyML.makestring ( sumPairs lst )) end;

Answer 1

NOTE:: If you have any query please ask in the comments section but do not give negative rating to the question as it affects my answering rights......I will help you out with your doubts...the program works fine i have tested it already.. you just need to copy pate them......GIVE A THUMBS UP !! if you like it

(1)

#include <iostream>
#include <list>
using namespace std;
list<list<int>> listify(list<int> lst){
    list<list<int>> result;
    list<int> tmp;//to make a temporary list which is then pushed to result 
    for(auto l:lst){
        tmp.push_back(l);
        result.push_back(tmp);
        tmp.clear();
    }
    return result;
}
int main() {
    list <int> lst={1,2,3,4,5,6};
    list<list<int>> res=listify(lst);
    cout<<"The result has following list of lists: ";
    for(auto i:res){
        cout<<"\nlist elements: ";
        for(auto j:i){
            cout<<j<<" ";
        }
    }
    return 0;
}

Output:-->

(2)

#include <iostream>
#include <list>
#include <vector>
using namespace std;
vector<pair<list<int>,list<int>>> splitlist(list<pair<int,int>> lst){
    vector<pair<list<int>,list<int>>> result;
    list<int> tmp1,tmp2;
    for(auto i:lst){
        tmp1.push_back(i.first);
        tmp2.push_back(i.second);
        result.push_back({tmp1,tmp2});
        tmp1.clear();
        tmp2.clear();
    }
    return result;
}
int main() {
    list <pair<int,int>> lst={{1,2},{3,4},{5,6},{7,8}};
    vector<pair<list<int>,list<int>>> res=splitlist(lst);
    cout<<"The result of the split function: ";
    for(auto i:res){
        cout<<"\nPair::\n";
        cout<<"\tfirst list elements: ";
        for(auto j:i.first){
            cout<<j<<" ";
        }
        cout<<"\n\tsecond list elements: ";
        for(auto k:i.second){
            cout<<k<<" ";
        }
    }
    return 0;
}

Output:-->

(3)

#include <iostream>
#include <list>
using namespace std;
list<int> sumPairs(list<pair<int,int>> lst){
    list<int> result;
    for(auto i:lst){
        result.push_back(i.first+i.second);
    }
    return result;
}
int main() {
    list <pair<int,int>> lst={{1,2},{3,4},{5,6},{7,8}};
    cout<<"The list of pairs is: "<<endl;
    for(auto i:lst){
       cout<<"{"<<i.first<<" "<<i.second<<"}"<<"\t";
    }
    list<int> res=sumPairs(lst);
    cout<<"\nThe result of the sumPairs function: "<<endl;
    for(auto i:res){
       cout<<i<<" ";
    }
    return 0;
}

Output:-->