1073. Adding Two Negabinary Numbers

Description

Given two numbers arr1 and arr2 in base -2, return the result of adding them together.

Each number is given in array format:  as an array of 0s and 1s, from most significant bit to least significant bit.  For example, arr = [1,1,0,1] represents the number (-2)^3 + (-2)^2 + (-2)^0 = -3.  A number arr in array, format is also guaranteed to have no leading zeros: either arr == [0] or arr[0] == 1.

Return the result of adding arr1 and arr2 in the same format: as an array of 0s and 1s with no leading zeros.

 

Example 1:

Input: arr1 = [1,1,1,1,1], arr2 = [1,0,1]
Output: [1,0,0,0,0]
Explanation: arr1 represents 11, arr2 represents 5, the output represents 16.

Example 2:

Input: arr1 = [0], arr2 = [0]
Output: [0]

Example 3:

Input: arr1 = [0], arr2 = [1]
Output: [1]

 

Constraints:

  • 1 <= arr1.length, arr2.length <= 1000
  • arr1[i] and arr2[i] are 0 or 1
  • arr1 and arr2 have no leading zeros

Solutions

Solution 1

Python Code
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class Solution:
    def addNegabinary(self, arr1: List[int], arr2: List[int]) -> List[int]:
        i, j = len(arr1) - 1, len(arr2) - 1
        c = 0
        ans = []
        while i >= 0 or j >= 0 or c:
            a = 0 if i < 0 else arr1[i]
            b = 0 if j < 0 else arr2[j]
            x = a + b + c
            c = 0
            if x >= 2:
                x -= 2
                c -= 1
            elif x == -1:
                x = 1
                c += 1
            ans.append(x)
            i, j = i - 1, j - 1
        while len(ans) > 1 and ans[-1] == 0:
            ans.pop()
        return ans[::-1]

Java Code
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class Solution {
    public int[] addNegabinary(int[] arr1, int[] arr2) {
        int i = arr1.length - 1, j = arr2.length - 1;
        List<Integer> ans = new ArrayList<>();
        for (int c = 0; i >= 0 || j >= 0 || c != 0; --i, --j) {
            int a = i < 0 ? 0 : arr1[i];
            int b = j < 0 ? 0 : arr2[j];
            int x = a + b + c;
            c = 0;
            if (x >= 2) {
                x -= 2;
                c -= 1;
            } else if (x == -1) {
                x = 1;
                c += 1;
            }
            ans.add(x);
        }
        while (ans.size() > 1 && ans.get(ans.size() - 1) == 0) {
            ans.remove(ans.size() - 1);
        }
        Collections.reverse(ans);
        return ans.stream().mapToInt(x -> x).toArray();
    }
}

C++ Code
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class Solution {
public:
    vector<int> addNegabinary(vector<int>& arr1, vector<int>& arr2) {
        int i = arr1.size() - 1, j = arr2.size() - 1;
        vector<int> ans;
        for (int c = 0; i >= 0 || j >= 0 || c; --i, --j) {
            int a = i < 0 ? 0 : arr1[i];
            int b = j < 0 ? 0 : arr2[j];
            int x = a + b + c;
            c = 0;
            if (x >= 2) {
                x -= 2;
                c -= 1;
            } else if (x == -1) {
                x = 1;
                c += 1;
            }
            ans.push_back(x);
        }
        while (ans.size() > 1 && ans.back() == 0) {
            ans.pop_back();
        }
        reverse(ans.begin(), ans.end());
        return ans;
    }
};

Go Code
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func addNegabinary(arr1 []int, arr2 []int) (ans []int) {
	i, j := len(arr1)-1, len(arr2)-1
	for c := 0; i >= 0 || j >= 0 || c != 0; i, j = i-1, j-1 {
		x := c
		if i >= 0 {
			x += arr1[i]
		}
		if j >= 0 {
			x += arr2[j]
		}
		c = 0
		if x >= 2 {
			x -= 2
			c -= 1
		} else if x == -1 {
			x = 1
			c += 1
		}
		ans = append(ans, x)
	}
	for len(ans) > 1 && ans[len(ans)-1] == 0 {
		ans = ans[:len(ans)-1]
	}
	for i, j = 0, len(ans)-1; i < j; i, j = i+1, j-1 {
		ans[i], ans[j] = ans[j], ans[i]
	}
	return ans
}

TypeScript Code
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function addNegabinary(arr1: number[], arr2: number[]): number[] {
    let i = arr1.length - 1,
        j = arr2.length - 1;
    const ans: number[] = [];
    for (let c = 0; i >= 0 || j >= 0 || c; --i, --j) {
        const a = i < 0 ? 0 : arr1[i];
        const b = j < 0 ? 0 : arr2[j];
        let x = a + b + c;
        c = 0;
        if (x >= 2) {
            x -= 2;
            c -= 1;
        } else if (x === -1) {
            x = 1;
            c += 1;
        }
        ans.push(x);
    }
    while (ans.length > 1 && ans[ans.length - 1] === 0) {
        ans.pop();
    }
    return ans.reverse();
}

C# Code
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public class Solution {
    public int[] AddNegabinary(int[] arr1, int[] arr2) {
        int i = arr1.Length - 1, j = arr2.Length - 1;
        List<int> ans = new List<int>();
        for (int c = 0; i >= 0 || j >= 0 || c != 0; --i, --j) {
            int a = i < 0 ? 0 : arr1[i];
            int b = j < 0 ? 0 : arr2[j];
            int x = a + b + c;
            c = 0;
            if (x >= 2) {
                x -= 2;
                c -= 1;
            } else if (x == -1) {
                x = 1;
                c = 1;
            }
            ans.Add(x);
        }
        while (ans.Count > 1 && ans[ans.Count - 1] == 0) {
            ans.RemoveAt(ans.Count - 1);
        }
        ans.Reverse();
        return ans.ToArray();
    }
}