79 lines
1.9 KiB
Rust
79 lines
1.9 KiB
Rust
/**
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* [447] Number of Boomerangs
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*
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* You are given n points in the plane that are all distinct, where points[i] = [xi, yi]. A boomerang is a tuple of points (i, j, k) such that the distance between i and j equals the distance between i and k (the order of the tuple matters).
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* Return the number of boomerangs.
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*
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* <strong class="example">Example 1:
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*
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* Input: points = [[0,0],[1,0],[2,0]]
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* Output: 2
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* Explanation: The two boomerangs are [[1,0],[0,0],[2,0]] and [[1,0],[2,0],[0,0]].
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*
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* <strong class="example">Example 2:
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*
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* Input: points = [[1,1],[2,2],[3,3]]
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* Output: 2
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*
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* <strong class="example">Example 3:
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*
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* Input: points = [[1,1]]
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* Output: 0
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*
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*
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* Constraints:
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*
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* n == points.length
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* 1 <= n <= 500
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* points[i].length == 2
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* -10^4 <= xi, yi <= 10^4
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* All the points are unique.
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*
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*/
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pub struct Solution {}
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// problem: https://leetcode.cn/problems/number-of-boomerangs/
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// discuss: https://leetcode.cn/problems/number-of-boomerangs/discuss/?currentPage=1&orderBy=most_votes&query=
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// submission codes start here
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use std::collections::HashMap;
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impl Solution {
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pub fn number_of_boomerangs(points: Vec<Vec<i32>>) -> i32 {
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let mut result = 0;
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for p in &points {
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let mut values = HashMap::new();
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for q in &points {
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let dis = (p[0] - q[0]).pow(2) + (p[1] - q[1]).pow(2);
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let c = values.entry(dis).or_insert(0);
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*c += 1;
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}
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for (_, v) in &values {
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// 实际上并不需要，因为最小值为1
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// 计算的结果为0
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if *v >= 2 {
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// result += A_m^2
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result += (*v) * (*v - 1);
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}
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}
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}
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result
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}
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}
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// submission codes end
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#[cfg(test)]
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mod tests {
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use super::*;
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#[test]
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fn test_447() {
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}
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}
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