some ds exercises fib and gcd lcm

ST4RGUARD · ST4RGUARD · commit cd4f363c5d1a · 2025-08-25T16:04:10.000-05:00
diff --git a/comp/rust/Cargo.lock b/comp/rust/Cargo.lock
diff --git a/comp/rust/Cargo.toml b/comp/rust/Cargo.toml
@@ -0,0 +1,6 @@
+[package]
+name = "rust"
+version = "0.1.0"
+edition = "2024"
+
+[dependencies]
diff --git a/comp/rust/src/main.rs b/comp/rust/src/main.rs
@@ -0,0 +1,17 @@
+use std::{i32, io};
+
+fn main() {
+    let mut input = String::new();
+
+    io::stdin().read_line(&mut input).expect("Failed to read line");
+
+    let mut nums = input
+        .trim()
+        .split_whitespace()
+        .map(|x| x.parse::<i32>().expect("Not a number"));
+
+    let n = nums.next().unwrap();
+    let m = nums.next().unwrap();
+
+
+}
diff --git a/comp/test.rb b/comp/test.rb
@@ -0,0 +1,37 @@
+alpha = ("a".."z")
+ref = {}
+
+alpha.each_with_index { |k, v| ref[k] = v }
+str1 = gets.chomp.downcase
+str2 = gets.chomp.downcase
+
+new_s1 = []
+new_s2 = []
+
+str1.split("").each do |i|
+  new_s1 << ref[i]
+end
+
+str2.split("").each do |i|
+  new_s2 << ref[i]
+end
+
+equal = 0
+
+new_s1.each_with_index do |val, i|
+  if val == new_s2[i]
+    equal = 1
+  elsif (val < new_s2[i])
+    equal = 0
+    puts("-1")
+    exit
+  else
+    equal = 0
+    puts("1")
+    exit
+  end
+end
+
+if equal == 1
+  puts("0")
+end
diff --git a/cpp/DSnA/fibonacci.cpp b/cpp/DSnA/fibonacci.cpp
@@ -0,0 +1,19 @@
+#include <iostream>
+using namespace std;
+
+int fib(int num) {
+  if (num <= 1) {
+    return num;
+  } else {
+    return fib(num - 1) + fib(num - 2);
+  }
+}
+
+int main() {
+    int num;
+    cin >> num;
+    
+    cout << fib(num) << endl;
+
+  return 0;
+}
diff --git a/cpp/DSnA/fibonacci_last.cpp b/cpp/DSnA/fibonacci_last.cpp
@@ -0,0 +1,37 @@
+#include <iostream>
+#include <string>
+#include <vector>
+using namespace std;
+
+vector<long long> cache;
+
+long long fib(int num) {
+  if (num == 0)
+    return 0;
+  if (num == 1)
+    return 1;
+
+  int first = 0, second = 1, next = 0;
+  for (int i = 2; i <= num; i++) {
+    next = (first + second) % 10;
+    first = second;
+    second = next;
+  }
+  return second;
+}
+
+void last(int num) {
+  string num_str = to_string(num);
+  char last_num = num_str.back();
+
+  cout << last_num << endl;
+}
+
+int main() {
+  int num;
+  cin >> num;
+
+  last(fib(num));
+
+  return 0;
+}
diff --git a/cpp/DSnA/fibonacci_memo.cpp b/cpp/DSnA/fibonacci_memo.cpp
@@ -0,0 +1,23 @@
+#include <iostream>
+#include <vector>
+using namespace std;
+
+vector<long long> cache;
+
+long long fib(int num) {
+    if (num <= 1) return num;
+    if (cache[num] != -1) return cache[num];
+
+    cache[num] = fib(num - 1) + fib(num - 2);
+    return cache[num];
+}
+
+int main() {
+    int num;
+    cin >> num;
+
+    cache.assign(num + 1, -1);
+
+    cout << fib(num) << endl;
+    return 0;
+}
diff --git a/cpp/DSnA/gcd.cpp b/cpp/DSnA/gcd.cpp
@@ -0,0 +1,23 @@
+#include <iostream>
+using namespace std;
+
+// gcd(a, b) = gcd(b, a % b)
+
+void gcd(int numA, int numB) {
+  while (numB != 0) {
+    int temp = numB;
+    numB = numA % numB;
+    numA = temp;
+  }
+
+  cout << numA << endl;
+}
+
+int main() {
+  int numA, numB;
+  cin >> numA >> numB;
+
+  gcd(numA, numB);
+
+  return 0;
+}
diff --git a/cpp/DSnA/lcm.cpp b/cpp/DSnA/lcm.cpp
@@ -0,0 +1,29 @@
+#include <iostream>
+using namespace std;
+
+// lcm = (a * b) / gcd(a, b)
+// to avoid overflow we divide first the multiply
+// lcm = (a / gcd(a, b)) * b
+
+long long gcd(long long numA, long long numB) {
+  while (numB != 0) {
+    long long temp = numB;
+    numB = numA % numB;
+    numA = temp;
+  }
+
+  return numA;
+}
+
+long long lcm(long long numA, long long numB) {
+  return (numA / gcd(numA, numB)) * numB;
+}
+
+int main() {
+  long long numA, numB;
+  cin >> numA >> numB;
+
+  cout << lcm(numA, numB) << endl;
+
+  return 0;
+}
diff --git a/cpp/DSnA/max_pairwise b/cpp/DSnA/max_pairwise
