Go and CPP snippets for quick reference

This blog is a snippet for my reference. I have many such snippets. Cheers.

1. Basic I/O setup.

#incldue<bits/stdc++.h>
using namespace std;

int main() {
   ios_base::sync_with_stdio(false);
   cin.tie(nullptr);

   return 0;
}

package main

import (
   "fmt"
   "bufio"
   "os"
)
   
func main() {
   in := bufio.NewReader(os.Stdin)
   out := bufio.NewWriter(os.Stdout)
   defer out.Flush()
}

2. Data Structures.

a. vector -> Slice

   vector<int> v = {1, 2, 3};
   v.push_back(4);

v := []int {1, 2, 3}
v = append(v, 4)

b. Set -> Map[Type]struct{}

#include<set>

set<int> s;
s.insert(1);
s.insert(2);

if(s.find(1) != s.end()) {
   // 1 is in set
}

package main

type void struct{}
var member void
   
s := make(map[int]void)
s[1] = member
s[2] = member

if _, exists := s[1]; exists {
   // 1 is in set.
}

3. Map -> map

#include<map>

map<string, int> m;
m["string"] = 42;

if(m.find("string") != m.end()) {
   cout << m["string"]
}

m := make(map[string]int)
m["key"] = 42

if value, exists := m["key"]; exists {
   fmt.Println(value)
}

4. Priority Queue -> container/heap

#include<queue>
priority_queue<int> pq;

pq.push(3);
pq.push(4);
while(!pq.empty()) {
   cout << pq.top() << "";
   pq.pop();
}

Create a type, implement Len, Less, Swap.

import (
   "container/heap"
   "fmt"
)

type IntHeap []int

func (h IntHeap) Len() int {return len(h)}

func (h IntHeap) Less(i, j int) bool {return h[i] > h[j]}

func (h IntHeap) Swap(i, j int) {h[i], h[j] = h[j], h[i]}
   
func (h *IntHeap) Push(x interface{}) {
   *h = append(*h, x.(int))
}

func (h *IntHeap) Pop() interface{} {
   old := *h
   n := len(old)
   x := old[n-1]
   *h = old[0: n-1]
   return x
}

func main() {
   h := &IntHeap{3, 1, 4}
   heap.Init(h)
   heap.Push(h, 2)
   for h.Len() > 0 {
      fmt.Println("%d", heap.Pop(h))
   }
}

5. Stack -> Slice.

#include<stack>
stack<int> s;
s.push(1);
s.push(2);
while(!s.empty()) {
   cout << s.top() << "\n";
   s.pop();
}

s := []int{}
s = append(s, 1)
s = append(s, 2)

for len(s) > 0 {
   fmt.Println("%d", s[len(s)-1])
   s = s[:len(s) - 1]
}

6. Queue -> slice

#include<queue>
queue<int> q;
q.push(1);
q.push(2);

while(!q.empty()) {
   cout << q.front() << " ";
   q.pop();
}

package main

q := []int{}
q = append(q, 1)
q = append(q, 2)

for len(q) > 0 {
   fmt.Println("%d", q[0])
   q = q[1:]
}

7. Pair -> struct

#include<utility>
pair<string, int> p = make_pair("one", 1);
cout << p.first <<  " " << p.second;

type Pair struct {
   First int
   Second string
}

p := Pair { 1, "one"}
fmt.Println(p.First, p.Second)

8. Linked list -> container/list

#include<list>
list<int> l;
l.push_back(1);
l.push_front(2);

for(auto it = l.begin(); it != l.end(); ++it) {
   cout << *it << " ";
}

package main

import (
   "fmt"
   "container/list"
)

l := list.New()
l.PushBack(1)
l.PushFront(2)

for e := l.Front(); e != nil; e = e.Next() {
   fmt.Printf("%v", e.Value)
}

9. Complete I/O for a sample t, n, m input and a comma separated integers input.

#include<bits/stdc++.h>
using namespace std;

void solve() {
   int n, m;
   cin >> n >> m;

   string arrStr;
   cin.ignore(); // Clear the newline c.
   getline(cin, arrStr);


   vector<int> arr;
   stringstream ss(arrStr);
   string numStr;
   while(getline(ss, numStr, ',')) {
      arr.push_back(stoi(numStr));
   }

   // Your solution logic here.
   // For this example, we'll just print the inputs.
}
int main() {
   ios_base::sync_with_stdio(false);
   cin.tie(nullptr);

   int t;
   cin >> t;
   while(t--) {
      solve();
   }
   return 0;
}

package main

import(
   "fmt"
   "bufio"
   "os"
   "strconv"
   "strings"
)

var scanner *bufio.Scanner
var writer *bufio.Writer

func init() {
   scanner = bufio.NewScanner(os.Stdin)
   scanner.Split(bufio.ScanWords)
   writer = bufio.NewWriter(os.Stdout)
}

func scanInt() int {
   scanner.Scan()
   num, _ := strconv.Atoi(scanner.Text())
   return num
}

func scanInts(n int) []int {
   nums := make([]int, n)
   for i:= 0; i < n; i++ {
      nums[i] = scanInt()
   }
   return nums
}

func scanLine() string {
   scanner.Scan()
   return scanner.Text()
}

func solve() {
   // Read two integers.
   n, m := scanInt(), scanInt()

   // Read comma separated integers.
   arrStr := scanLine()
   strNums := strings.Split(arrStr, ",")
   arr := make([]int, len(strNums))
   for i, numStr := range strNums {
      arr[i], _ = strconv.Atoi(numStr)
   }
}

func scanInts() []int {
   scanner.Scan()
   return scanner.Text()
}

func main() {
   defer writer.Flush()

   t := scanInt()

   for i := 0; i<t; i++ {
      solve()
   }
}