Earliest Finish Time for Land and Water Rides I solution and explanation

class Solution:
    def earliestFinishTime(self, landStartTime: List[int], landDuration: List[int], waterStartTime: List[int], waterDuration: List[int]) -> int:
        def calc(a1, t1, a2, t2):
            min_end = min(a + t for a, t in zip(a1, t1))
            return min(max(a, min_end) + t for a, t in zip(a2, t2))

        x = calc(landStartTime, landDuration, waterStartTime, waterDuration)
        y = calc(waterStartTime, waterDuration, landStartTime, landDuration)
        return min(x, y)

class Solution {
    public int earliestFinishTime(
        int[] landStartTime, int[] landDuration, int[] waterStartTime, int[] waterDuration) {
        int x = calc(landStartTime, landDuration, waterStartTime, waterDuration);
        int y = calc(waterStartTime, waterDuration, landStartTime, landDuration);
        return Math.min(x, y);
    }

    private int calc(int[] a1, int[] t1, int[] a2, int[] t2) {
        int minEnd = Integer.MAX_VALUE;
        for (int i = 0; i < a1.length; ++i) {
            minEnd = Math.min(minEnd, a1[i] + t1[i]);
        }
        int ans = Integer.MAX_VALUE;
        for (int i = 0; i < a2.length; ++i) {
            ans = Math.min(ans, Math.max(minEnd, a2[i]) + t2[i]);
        }
        return ans;
    }
}

class Solution {
public:
    int earliestFinishTime(vector<int>& landStartTime, vector<int>& landDuration, vector<int>& waterStartTime, vector<int>& waterDuration) {
        int x = calc(landStartTime, landDuration, waterStartTime, waterDuration);
        int y = calc(waterStartTime, waterDuration, landStartTime, landDuration);
        return min(x, y);
    }

    int calc(vector<int>& a1, vector<int>& t1, vector<int>& a2, vector<int>& t2) {
        int minEnd = INT_MAX;
        for (int i = 0; i < a1.size(); ++i) {
            minEnd = min(minEnd, a1[i] + t1[i]);
        }
        int ans = INT_MAX;
        for (int i = 0; i < a2.size(); ++i) {
            ans = min(ans, max(minEnd, a2[i]) + t2[i]);
        }
        return ans;
    }
};

function earliestFinishTime(
    landStartTime: number[],
    landDuration: number[],
    waterStartTime: number[],
    waterDuration: number[],
): number {
    const x = calc(landStartTime, landDuration, waterStartTime, waterDuration);
    const y = calc(waterStartTime, waterDuration, landStartTime, landDuration);
    return Math.min(x, y);
}

function calc(a1: number[], t1: number[], a2: number[], t2: number[]): number {
    let minEnd = Number.MAX_SAFE_INTEGER;
    for (let i = 0; i < a1.length; i++) {
        minEnd = Math.min(minEnd, a1[i] + t1[i]);
    }
    let ans = Number.MAX_SAFE_INTEGER;
    for (let i = 0; i < a2.length; i++) {
        ans = Math.min(ans, Math.max(minEnd, a2[i]) + t2[i]);
    }
    return ans;
}

func earliestFinishTime(landStartTime []int, landDuration []int, waterStartTime []int, waterDuration []int) int {
	x := calc(landStartTime, landDuration, waterStartTime, waterDuration)
	y := calc(waterStartTime, waterDuration, landStartTime, landDuration)
	return min(x, y)
}

func calc(a1 []int, t1 []int, a2 []int, t2 []int) int {
	minEnd := math.MaxInt32
	for i := 0; i < len(a1); i++ {
		minEnd = min(minEnd, a1[i]+t1[i])
	}
	ans := math.MaxInt32
	for i := 0; i < len(a2); i++ {
		ans = min(ans, max(minEnd, a2[i])+t2[i])
	}
	return ans
}