feat: 2364_count_number_of_bad_pairs

2364_count_number_of_bad_pairs/Cargo.lock

@@ -0,0 +1,7 @@
+# This file is automatically @generated by Cargo.
+# It is not intended for manual editing.
+version = 4
+
+[[package]]
+name = "count_number_of_bad_pairs"
+version = "0.1.0"

2364_count_number_of_bad_pairs/Cargo.toml

@@ -0,0 +1,6 @@
+[package]
+name = "count_number_of_bad_pairs"
+version = "0.1.0"
+edition = "2024"
+
+[dependencies]

2364_count_number_of_bad_pairs/src/lib.rs

@@ -0,0 +1,23 @@
+pub struct Solution;
+
+impl Solution {
+    pub fn count_bad_pairs(nums: Vec<i32>) -> i64 {
+        let mut groups = std::collections::HashMap::<i32, i64>::new();
+
+        for (index, num) in nums.iter().enumerate() {
+            let index_sub_num = index as i32 - *num;
+            groups
+                .entry(index_sub_num)
+                .and_modify(|count| *count += 1)
+                .or_insert(1);
+        }
+
+        let total_comb = Solution::count_pairs(&(nums.len() as i64));
+        let same_comb: i64 = groups.values().map(Solution::count_pairs).sum();
+        total_comb - same_comb
+    }
+
+    fn count_pairs(n: &i64) -> i64 {
+        n * (n - 1) / 2
+    }
+}