Question

1281. Subtract the Product and Sum of Digits of an Integer

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Description

Given an integer number n, return the difference between the product of its digits and the sum of its digits.

 

Example 1:

Input: n = 234
Output: 15 
Explanation: 
Product of digits = 2 * 3 * 4 = 24 
Sum of digits = 2 + 3 + 4 = 9 
Result = 24 - 9 = 15

Example 2:

Input: n = 4421
Output: 21
Explanation: 
Product of digits = 4 * 4 * 2 * 1 = 32 
Sum of digits = 4 + 4 + 2 + 1 = 11 
Result = 32 - 11 = 21

 

Constraints:

• 1 <= n <= 10^5

Solutions

Solution 1: Simulation

We use two variables $x$ and $y$ to record the product of the digits and the sum of the digits respectively. At the beginning, $x=1,y=0$.

When $n \gt 0$, each time we take the $mod$ of $n$ by $10$ to get the current digit $v$, and continue the next loop by dividing $n$ by $10$. In each loop, we update $x = x \times v$, $y = y + v$.

Finally, we return $x - y$.

The time complexity is $O(\log n)$, where $n$ is the given integer. The space complexity is $O(1)$.

class Solution:
  def subtractProductAndSum(self, n: int) -> int:
    x, y = 1, 0
    while n:
      n, v = divmod(n, 10)
      x *= v
      y += v
    return x - y

class Solution {
  public int subtractProductAndSum(int n) {
    int x = 1, y = 0;
    for (; n > 0; n /= 10) {
      int v = n % 10;
      x *= v;
      y += v;
    }
    return x - y;
  }
}

class Solution {
public:
  int subtractProductAndSum(int n) {
    int x = 1, y = 0;
    for (; n; n /= 10) {
      int v = n % 10;
      x *= v;
      y += v;
    }
    return x - y;
  }
};

func subtractProductAndSum(n int) int {
  x, y := 1, 0
  for ; n > 0; n /= 10 {
    v := n % 10
    x *= v
    y += v
  }
  return x - y
}

function subtractProductAndSum(n: number): number {
  let [x, y] = [1, 0];
  for (; n > 0; n = Math.floor(n / 10)) {
    const v = n % 10;
    x *= v;
    y += v;
  }
  return x - y;
}

impl Solution {
  pub fn subtract_product_and_sum(mut n: i32) -> i32 {
    let mut x = 1;
    let mut y = 0;
    while n != 0 {
      let v = n % 10;
      n /= 10;
      x *= v;
      y += v;
    }
    x - y
  }
}

public class Solution {
  public int SubtractProductAndSum(int n) {
    int x = 1;
    int y = 0;
    for (; n > 0; n /= 10) {
      int v = n % 10;
      x *= v;
      y += v;
    }
    return x - y;
  }
}

int subtractProductAndSum(int n) {
  int x = 1;
  int y = 0;
  for (; n > 0; n /= 10) {
    int v = n % 10;
    x *= v;
    y += v;
  }
  return x - y;
}

Solution 2

class Solution:
  def subtractProductAndSum(self, n: int) -> int:
    nums = list(map(int, str(n)))
    return prod(nums) - sum(nums)