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# Ways to write n as sum of two or more positive integers

• Difficulty Level : Medium
• Last Updated : 20 Dec, 2022

For a given number n > 0, find the number of different ways in which n can be written as a sum of two or more positive integers.

Examples:

```Input : n = 5
Output : 6
Explanation : All possible six ways are :
4 + 1
3 + 2
3 + 1 + 1
2 + 2 + 1
2 + 1 + 1 + 1
1 + 1 + 1 + 1 + 1

Input : 4
Output : 4
Explanation : All possible four ways are :
3 + 1
2 + 2
2 + 1 + 1
1 + 1 + 1 + 1```
Recommended Practice

This problem can be solved in a similar fashion as coin change problem, the difference is only that in this case we should iterate for 1 to n-1 instead of particular values of coin as in coin-change problem.

## C++

 `// Program to find the number of ways, n can be ` `// written as sum of two or more positive integers. ` `#include ` `using` `namespace` `std; `   `// Returns number of ways to write n as sum of ` `// two or more positive integers ` `int` `countWays(``int` `n) ` `{ ` `    ``// table[i] will be storing the number of ` `    ``// solutions for value i. We need n+1 rows ` `    ``// as the table is constructed in bottom up ` `    ``// manner using the base case (n = 0) ` `    ``int` `table[n+1]; `   `    ``// Initialize all table values as 0 ` `    ``memset``(table, 0, ``sizeof``(table)); `   `    ``// Base case (If given value is 0) ` `    ``table[0] = 1; `   `    ``// Pick all integer one by one and update the ` `    ``// table[] values after the index greater ` `    ``// than or equal to n ` `    ``for` `(``int` `i=1; i

## Java

 `// Program to find the number of ways, ` `// n can be written as sum of two or ` `// more positive integers.` `import` `java.util.Arrays;`   `class` `GFG {` `    `  `    ``// Returns number of ways to write` `    ``// n as sum of two or more positive ` `    ``// integers` `    ``static` `int` `countWays(``int` `n)` `    ``{` `        `  `        ``// table[i] will be storing the ` `        ``// number of solutions for value` `        ``// i. We need n+1 rows as the ` `        ``// table is constructed in bottom` `        ``// up manner using the base case` `        ``// (n = 0)` `        ``int` `table[] = ``new` `int``[n + ``1``];` `    `  `        ``// Initialize all table values as 0` `        ``Arrays.fill(table, ``0``);` `    `  `        ``// Base case (If given value is 0)` `        ``table[``0``] = ``1``;` `    `  `        ``// Pick all integer one by one and` `        ``// update the table[] values after ` `        ``// the index greater than or equal ` `        ``// to n` `        ``for` `(``int` `i = ``1``; i < n; i++)` `            ``for` `(``int` `j = i; j <= n; j++)` `                ``table[j] += table[j - i];` `    `  `        ``return` `table[n];` `    ``}` `    `  `    ``//driver code` `    ``public` `static` `void` `main (String[] args)` `    ``{` `        ``int` `n = ``7``;` `        `  `        ``System.out.print(countWays(n));` `    ``}` `}`   `// This code is contributed by Anant Agarwal.`

## Python3

 `# Program to find the number of ways, n can be` `# written as sum of two or more positive integers.`   `# Returns number of ways to write n as sum of` `# two or more positive integers` `def` `CountWays(n):`   `    ``# table[i] will be storing the number of` `    ``# solutions for value i. We need n+1 rows` `    ``# as the table is constructed in bottom up` `    ``# manner using the base case (n = 0)` `    ``# Initialize all table values as 0` `    ``table ``=``[``0``] ``*` `(n ``+` `1``)`   `    ``# Base case (If given value is 0)` `    ``# Only 1 way to get 0 (select no integer)` `    ``table[``0``] ``=` `1`   `    ``# Pick all integer one by one and update the` `    ``# table[] values after the index greater` `    ``# than or equal to n` `    ``for` `i ``in` `range``(``1``, n ):`   `        ``for` `j ``in` `range``(i , n ``+` `1``):`   `            ``table[j] ``+``=`  `table[j ``-` `i]            `   `    ``return` `table[n]`   `# driver program` `def` `main():`   `    ``n ``=` `7`   `    ``print` `(CountWays(n))`   `if` `__name__ ``=``=` `'__main__'``:` `    ``main()`   `#This code is contributed by Neelam Yadav`

## C#

 `// Program to find the number of ways, n can be` `// written as sum of two or more positive integers.` `using` `System;`   `class` `GFG {` `    `  `    ``// Returns number of ways to write n as sum of` `    ``// two or more positive integers` `    ``static` `int` `countWays(``int` `n)` `    ``{` `        `  `        ``// table[i] will be storing the number of` `        ``// solutions for value i. We need n+1 rows` `        ``// as the table is constructed in bottom up` `        ``// manner using the base case (n = 0)` `        ``int` `[]table = ``new` `int``[n+1];` `     `  `        ``// Initialize all table values as 0` `        ``for``(``int` `i = 0; i < table.Length; i++)` `            ``table[i] = 0;` `     `  `        ``// Base case (If given value is 0)` `        ``table[0] = 1;` `     `  `        ``// Pick all integer one by one and update the` `        ``// table[] values after the index greater` `        ``// than or equal to n` `        ``for` `(``int` `i = 1; i < n; i++)` `            ``for` `(``int` `j = i; j <= n; j++)` `                ``table[j] += table[j-i];` `     `  `        ``return` `table[n];` `    ``}` `    `  `    ``//driver code` `    ``public` `static` `void` `Main()` `    ``{` `        ``int` `n = 7;` `        `  `        ``Console.Write(countWays(n));` `    ``}` `}`   `// This code is contributed by Anant Agarwal.`

## PHP

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## Javascript

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Output

`14`

Time Complexity: O(n2)
Auxiliary Space: O(n)

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