heap.rs

struct Heap {
    data: Vec<i32>
}

impl Heap {
    fn from(arr: &[i32]) -> Heap {
        let mut h = Heap { data: Vec::from(arr)};
        h.make();
        return h;
    }

    fn sift_down(&mut self, x: usize) {
        let mut i = x;
        let mut l;
        let mut r;
        let mut greater = i;
        while i < self.data.len() {
            l = i * 2 + 1;
            r = i * 2 + 2;
            if l >= self.data.len() {
                break;
            }

            if self.data[i] < self.data[l] {
                greater = l;
            }

            if r < self.data.len() && self.data[greater] < self.data[r] {
                greater = r;
            }

            if greater == i {
                break;
            }

            let temp = self.data[greater];
            self.data[greater] = self.data[i];
            self.data[i] = temp;
            i = greater;
        }
    }

    fn make(&mut self) {
        for x in (0..self.data.len()).rev() {
            self.sift_down(x);
        }
    }

    fn pop(&mut self) -> i32 {
        let ris = self.data[0];
        self.data[0] = self.data[self.data.len() - 1];
        self.data.pop();
        self.sift_down(0);
        return ris;
    }
}