LeetCode Entry

1665. Minimum Initial Energy to Finish Tasks

12.05.2026 hard 2026 kotlin rust

Energy for all tasks (spend, limit)

1665. Minimum Initial Energy to Finish Tasks hard substack youtube

https://dmitrysamoylenko.com/leetcode/

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Problem TLDR

Energy for all tasks (spend, limit)

Intuition

    // we can do binary search
    // but how to optimally use the energy?
    // do we know that order is always decrease t[][1]?
    //
    // i don't have any better idea, let's write bs

    // 32
    // 10-12, 10-11, 8-9, 2-4, 1-3
    //        22     12   4    2     so this is the corner case
    //
    // 1-3 2-4 10-11 10-12 8-9
    // 32  31  29    19    9       this is the optimal order
    //
    // 26 minute, hints: Figure a sorting pattern
    //                   is exactly what i can't do
    //
    // so this is a brainteaser about sorting
    //

Didn’t solve without a hint. Sort by (spend-limit). Then do a binary search with forward pass and energy consumption or just a backward pass and energy max(spend, limit). The intuition behind (spend-limit): it is a greedy assumption that minimizing the consumption works. Why the pair of (spend,-limit) or (-limit, spend) doesn’t work? Because we want to maximize the “refund” (what was required - what was returned back).

Approach

• rust itertools allows one-liner

Complexity

• Time complexity: \(O(nlogn)\)

• Space complexity: \(O(1)\)

Code

    fun minimumEffort(t: Array<IntArray>) = t
        .sortedBy { it[1]-it[0] }
        .fold(0) { e, (a,b) -> max(e+a, b) }

    pub fn minimum_effort(t: Vec<Vec<i32>>) -> i32 {
        t.iter().sorted_by_key(|v|v[1]-v[0])
        .fold(0, |e, v| v[1].max(e+v[0]))
    }