54 lines
1.5 KiB
Rust
54 lines
1.5 KiB
Rust
// 建堆，自底向上堆化
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pub fn build_heap_down_up(nums: &mut Vec<i32>) {
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for i in 1..nums.len() {
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heapify_down_up(nums, i);
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}
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}
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fn heapify_down_up(nums: &mut Vec<i32>, idx: usize) {
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let mut idx = idx;
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let mut parent_idx = idx - 1 >> 1;
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while nums[idx] > nums[parent_idx] {
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swap(nums, idx, parent_idx);
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idx = parent_idx;
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if idx == 0 { break; }
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parent_idx = idx - 1 >> 1;
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}
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}
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// 建堆，自上向下堆化
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pub fn build_heap_up_down(nums: &mut Vec<i32>) {
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let nums_len = nums.len();
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for i in (0..nums_len).rev() {
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heapify_up_down(nums, i, nums_len);
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}
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}
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fn heapify_up_down(nums: &mut Vec<i32>, idx: usize, nums_len: usize) {
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let mut idx = idx;
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loop {
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let mut max_pos = idx;
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if 2 * idx + 1 < nums_len && nums[idx] < nums[2 * idx + 1] { max_pos = 2 * idx + 1; }
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if 2 * idx + 2 < nums_len && nums[max_pos] < nums[2 * idx + 2] { max_pos = 2 * idx + 2; }
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if max_pos == idx { break; }
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swap(nums, idx, max_pos);
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idx = max_pos;
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}
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}
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fn swap(nums: &mut Vec<i32>, idx: usize, parent_idx: usize) {
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let tmp = nums[parent_idx];
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nums[parent_idx] = nums[idx];
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nums[idx] = tmp;
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}
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fn main() {
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let mut nums = vec![1, 4, 5, 7, 8, 13, 16, 19, 20];
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build_heap_down_up(&mut nums);
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println!("{:?}", nums);
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let mut nums1 = vec![1, 4, 5, 7, 8, 13, 16, 19, 20];
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build_heap_up_down(&mut nums1);
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println!("{:?}", nums1);
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}
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