solve: 1218. Longest Arithmetic Subsequence of Given Difference in rust & golang

Signed-off-by: rajput-hemant <[email protected]>

Author: rajput-hemant

src/1201-1300/1218 - Longest Arithmetic Subsequence of Given Difference/longest_arithmetic_subsequence_of_given_difference.go

@@ -0,0 +1,19 @@
+package main
+
+func longestSubsequence(arr []int, difference int) int {
+	dp := make(map[int]int)
+
+	for _, v := range arr {
+		dp[v] = dp[v-difference] + 1
+	}
+
+	max := 0
+
+	for _, v := range dp {
+		if v > max {
+			max = v
+		}
+	}
+
+	return max
+}

src/1201-1300/1218 - Longest Arithmetic Subsequence of Given Difference/longest_arithmetic_subsequence_of_given_difference.rs

@@ -0,0 +1,12 @@
+impl Solution {
+    pub fn longest_subsequence(arr: Vec<i32>, difference: i32) -> i32 {
+        *arr.iter()
+            .fold(HashMap::new(), |mut map, &i| {
+                map.insert(i, map.get(&(i - difference)).unwrap_or(&0) + 1);
+                map
+            })
+            .values()
+            .max()
+            .unwrap()
+    }
+}