Handy Miscellaneous Tricks and Tips.md

• Convert string to integer: stoi(string);

• Convert integer to string: to_string(integer);

• Check if space is present in string: isspace();

• Check if string contains alphabet: isalpha(char);

• Remove duplicates from vector: ans.erase(unique ( ans.begin(), ans.end() ), ans.end() ); For more methods check Techie Delight's article

• Remove all occurences of a char in string: str.erase(std::remove(str.begin(), str.end(), 'a'), str.end());

• Find lexicographically previous smaller permutation: prev_permutation(str.begin(), str.end());

• Find lexicographically next larger permutation: next_permutation(str.begin(), str.end());

• Convert decimal to binary number :
  `#include<stdio.h>

     void main()
   {
        unsigned int num;
        int i;
        scanf("%u", &num);
        for (i = 0; i < 16; i++)
        printf("%d", (num << i & 1 << 15)? 1:0);
   }`
  

Another method: `

 ` #include<iostream>

   #include<string>

   #include <bitset>

   using namespace std;

   int main()

 {
 
int n=128;

string binary = bitset<8>(n).to_string(); //to binary
cout<<binary<<"\n";

unsigned long decimal = bitset<8>(binary).to_ulong();
cout<<decimal<<"\n";
return 0;
  }`

• Convert string to integer:

` #include <stdio.h>

#include <string.h>

main()

{

char num[50];

int i, len;

int result=0;

printf("Enter a number: ");

gets(num);

len = strlen(num);

for(i=0; i<len; i++) { result = result * 10 + ( num[i] - '0' ); }

printf("%d", result);

} `

• Prefix Sum Array Applications in Competitive Programming
• Tuples in C++ STL