2270_number_of_ways_to_split_array.cpp

#include <bits/stdc++.h>

using namespace std;

class Solution {
public:
    int waysToSplitArray(vector<int>& nums) {
        int n = nums.size();
        long long totalSum = 0;
        for (auto x : nums) {
            totalSum += x;
        }
        int numOfWays = 0;
        long long leftSum = 0;
        for (int i = 0; i < n - 1; ++i) {
            leftSum += nums[i];
            totalSum -= nums[i];
            if (leftSum >= totalSum) {
                ++numOfWays;
            }
        }
        return numOfWays;
    }
};

int main() {
    ios_base::sync_with_stdio(false);
    cin.tie(nullptr);
    vector<int> nums = {10, 4, -8, 7};
    Solution solve;
    int result = solve.waysToSplitArray(nums);
    cout << result << '\n';
    return 0;
}

/*
    ------------------
    Problem Statement:
    ------------------

    You are given a 0-indexed integer array nums of length n.

    nums contains a valid split at index i if the following are true:

    The sum of the first i + 1 elements is greater than or equal to the sum of the last n - i - 1 elements.
    There is at least one element to the right of i. That is, 0 <= i < n - 1.
    Return the number of valid splits in nums.

    ----------
    Example 1:
    ----------

    Input: nums = [10,4,-8,7]
    Output: 2
    Explanation: 
    There are three ways of splitting nums into two non-empty parts:
    - Split nums at index 0. Then, the first part is [10], and its sum is 10. The second part is [4,-8,7], and its sum is 3. Since 10 >= 3, i = 0 is a valid split.
    - Split nums at index 1. Then, the first part is [10,4], and its sum is 14. The second part is [-8,7], and its sum is -1. Since 14 >= -1, i = 1 is a valid split.
    - Split nums at index 2. Then, the first part is [10,4,-8], and its sum is 6. The second part is [7], and its sum is 7. Since 6 < 7, i = 2 is not a valid split.
    Thus, the number of valid splits in nums is 2.

    ----------
    Example 2:
    ----------

    Input: nums = [2,3,1,0]
    Output: 2
    Explanation: 
    There are two valid splits in nums:
    - Split nums at index 1. Then, the first part is [2,3], and its sum is 5. The second part is [1,0], and its sum is 1. Since 5 >= 1, i = 1 is a valid split. 
    - Split nums at index 2. Then, the first part is [2,3,1], and its sum is 6. The second part is [0], and its sum is 0. Since 6 >= 0, i = 2 is a valid split.
    
    ------------
    Constraints:
    ------------

    2 <= nums.length <= 10^5
    -10^5 <= nums[i] <= 10^5
*/