diff --git a/src/solution/mod.rs b/src/solution/mod.rs index 2452bc2..854953f 100644 --- a/src/solution/mod.rs +++ b/src/solution/mod.rs @@ -13,3 +13,4 @@ mod s0006_zigzag_conversion; mod s0007_reverse_integer; mod s0004_median_of_two_sorted_arrays; mod s0743_network_delay_time; +mod s0447_number_of_boomerangs; diff --git a/src/solution/s0447_number_of_boomerangs.rs b/src/solution/s0447_number_of_boomerangs.rs new file mode 100644 index 0000000..8d46d56 --- /dev/null +++ b/src/solution/s0447_number_of_boomerangs.rs @@ -0,0 +1,78 @@ +/** + * [447] Number of Boomerangs + * + * 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). + * Return the number of boomerangs. + * + * Example 1: + * + * Input: points = [[0,0],[1,0],[2,0]] + * Output: 2 + * Explanation: The two boomerangs are [[1,0],[0,0],[2,0]] and [[1,0],[2,0],[0,0]]. + * + * Example 2: + * + * Input: points = [[1,1],[2,2],[3,3]] + * Output: 2 + * + * Example 3: + * + * Input: points = [[1,1]] + * Output: 0 + * + * + * Constraints: + * + * n == points.length + * 1 <= n <= 500 + * points[i].length == 2 + * -10^4 <= xi, yi <= 10^4 + * All the points are unique. + * + */ +pub struct Solution {} + +// problem: https://leetcode.cn/problems/number-of-boomerangs/ +// discuss: https://leetcode.cn/problems/number-of-boomerangs/discuss/?currentPage=1&orderBy=most_votes&query= + +// submission codes start here + +use std::collections::HashMap; +impl Solution { + pub fn number_of_boomerangs(points: Vec>) -> i32 { + let mut result = 0; + + for p in &points { + let mut values = HashMap::new(); + + for q in &points { + let dis = (p[0] - q[0]).pow(2) + (p[1] - q[1]).pow(2); + + let c = values.entry(dis).or_insert(0); + *c += 1; + } + + for (_, v) in &values { + // 实际上并不需要,因为最小值为1 + // 计算的结果为0 + if *v >= 2 { + // result += A_m^2 + result += (*v) * (*v - 1); + } + } + } + + result + } +} + +// submission codes end + +#[cfg(test)] +mod tests { + use super::*; + + #[test] + fn test_447() { + } +}