leetcode/lc1648/code.rs

impl Solution {
    fn count_above_exec(inventory: &Vec<i32>, threshold: i64) -> i64 {
        let n = inventory.len();
        let mut count: i64 = 0;
        let mut j: usize = 0;
        while j < n {
            if inventory[j] as i64 > threshold {
                count += inventory[j] as i64 - threshold;
            }
            j += 1;
        }
        count
    }

    pub fn max_profit(inventory: Vec<i32>, orders: i32) -> i32 {
        let n = inventory.len();
        let orders_i64 = orders as i64;
        let modulo: i128 = 1_000_000_007;

        let mut max_inv: i64 = 0;
        let mut i: usize = 0;
        while i < n {
            if inventory[i] as i64 > max_inv {
                max_inv = inventory[i] as i64;
            }
            i += 1;
        }

        let mut lo: i64 = 0;
        let mut hi: i64 = max_inv;
        while lo < hi {
            let mid = lo + (hi - lo) / 2;
            let count = Self::count_above_exec(&inventory, mid);
            if count <= orders_i64 {
                hi = mid;
            } else {
                lo = mid + 1;
            }
        }

        let threshold = lo;
        let mut total: i128 = 0;
        let mut sold: i64 = 0;
        let mut k: usize = 0;
        while k < n {
            let inv = inventory[k] as i64;
            if inv > threshold {
                sold += inv - threshold;
                let inv128 = inv as i128;
                let thr128 = threshold as i128;
                let a = inv128 + thr128 + 1;
                let b = inv128 - thr128;
                let contrib = (inv128 + thr128 + 1) * (inv128 - thr128) / 2;
                total += contrib;
            }
            k += 1;
        }

        let rem128 = (orders_i64 - sold) as i128;
        let thr_rem = threshold as i128;

        total += rem128 * thr_rem;

        (total % modulo) as i32
    }
}