Some important shortcuts in Competitive Programming

The most common tools to save time in C/C++ are typedefs and macros. Unfortunately, these features are not available in many other languages like Java.

Here are some examples of our C/C++ code

Shortcuts:

// Shortcuts for "common" data types in contests
typedef long long ll; 
typedef pair<int, int> ii; 
typedef vector<ii> vii;
typedef vector<int> vi;

Infinite:

const int INF = 0x3f3f3f3f;

Setting up values in array:

// initialize DP memoization table with -1
memset(memo, -1, sizeof memo); 

// to clear array of integers
memset(arr, 0, sizeof arr); 

// Use a vector to creates a dynamic array 
// and initialize it in one statement.
// Creates a vector of size N and values as 0.
vector<int> v(N, 0); // OR vi v(N, 0); 

The following shortcuts can save time in almost all languages including Java:

// to simplify: if (a) ans = b; else ans = c;
ans = a ? b : c; 

// to simplify: ans = ans + val; and its variants
ans += val; 

// index++; if (index >= n) index = 0;
index = (index + 1) % n; 

// index--; if (index < 0) index = n - 1;
index = (index + n - 1) % n; 

// for rounding to nearest integer
int ans = (int)((double)d + 0.5); 

// min/max shortcut to update max/min
ans = min(ans, new_computation); 

// To return true if a value matches a given
// number, else return false
// if (val == given_no) return true; 
// else return false;
return (val == given_no)

This article is contributed by Priyam kakati. Please write comments if you find anything incorrect, or you want to share more information about the topic discussed above



My Personal Notes arrow_drop_up


Article Tags :

4


Please write to us at contribute@geeksforgeeks.org to report any issue with the above content.