From f702a6fc99abb02069f75e9017df7bbd734c11af Mon Sep 17 00:00:00 2001
From: Felix Martin <mail@felixm.de>
Date: Mon, 15 Feb 2021 13:02:17 -0500
Subject: [PATCH] Finish course 3 week 3 assignment

---
 src/main.rs | 13 +++++++++++-
 src/mwis.rs | 60 +++++++++++++++++++++++++++++++++++++++++++++++++++++
 src/util.rs | 21 +++++++++++++++++++
 3 files changed, 93 insertions(+), 1 deletion(-)
 create mode 100644 src/mwis.rs

diff --git a/src/main.rs b/src/main.rs
index 0b43178..9569690 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -4,6 +4,7 @@ mod huffman;
 mod jobs;
 mod k_clustering;
 mod k_clustering_big;
+mod mwis;
 mod merge_sort;
 mod min_cut;
 mod prims;
@@ -23,6 +24,7 @@ use crate::prims::prims;
 use crate::quick_sort::quick_sort;
 use crate::ssc::ssc;
 use crate::two_sum::find_two_sums;
+use crate::mwis::mwis;
 use std::cmp::min;
 
 #[allow(dead_code)]
@@ -120,7 +122,15 @@ fn c3a2() {
 fn c3a3() {
     let h = util::read_huffman_alphabet("data/c3a3_huffman.txt").unwrap();
     let r = huffman::build_huffman_tree(&h);
-    println!("r1 = {} r2 = {}", r.1, r.0);
+
+    let s = util::read_max_weight_set("data/c3a3_mwis.txt").unwrap();
+    let r3 = mwis(&s);
+    println!("r1 = {} r2 = {} r3 = {:?}", r.1, r.0, r3);
+}
+
+#[allow(dead_code)]
+fn c3a4() {
+	println!("continue here");
 }
 
 fn main() {
@@ -134,4 +144,5 @@ fn main() {
     // c3a1();
     // c3a2();
     c3a3();
+    c3a4();
 }
diff --git a/src/mwis.rs b/src/mwis.rs
new file mode 100644
index 0000000..28aeee2
--- /dev/null
+++ b/src/mwis.rs
@@ -0,0 +1,60 @@
+
+#[derive(Debug)]
+pub struct IndependentSet {
+    pub length: usize,
+    pub weights: Vec<u64>,
+}
+
+#[derive(Debug)]
+struct Solution {
+	weight: u64,
+	nodes: Vec<usize>,
+}
+
+pub fn mwis(s: &IndependentSet) -> Vec<usize> {
+	let mut solutions: Vec<Solution> = Vec::new();
+
+
+	solutions.push(Solution {
+		weight: s.weights[0],
+		nodes: vec![0],
+	});
+
+	solutions.push(Solution {
+		weight: s.weights[1],
+		nodes: vec![1],
+	});
+
+	for i in 2..s.weights.len() {
+		let s1 = Solution {
+			weight: solutions[i - 1].weight,
+			nodes: solutions[i - 1].nodes.to_vec(),
+		};
+
+		let mut s2_vec = solutions[i - 2].nodes.to_vec();
+		s2_vec.push(i);
+		let s2 = Solution {
+			weight: solutions[i - 2].weight + s.weights[i],
+			nodes: s2_vec,
+		};
+
+		if s1.weight > s2.weight {
+			solutions.push(s1);
+		} else {
+			solutions.push(s2);
+		}
+
+	}
+
+	let solution = solutions.pop().unwrap();
+	let mut result = Vec::new();
+	let vertices = vec![0, 1, 2, 3, 16, 116, 516, 996];
+	for v in &vertices {
+		if solution.nodes.contains(v) {
+			result.push(1);
+		} else {
+			result.push(0);
+		}
+	}
+	result
+}
\ No newline at end of file
diff --git a/src/util.rs b/src/util.rs
index 3f55aa8..5d0ed5d 100644
--- a/src/util.rs
+++ b/src/util.rs
@@ -5,6 +5,7 @@ use crate::k_clustering_big;
 use crate::min_cut;
 use crate::prims;
 use crate::ssc;
+use crate::mwis;
 use std::fs::File;
 use std::io;
 use std::io::{BufRead, BufReader, Error, ErrorKind};
@@ -260,3 +261,23 @@ pub fn read_huffman_alphabet(path: &str) -> Result<huffman::HuffmanAlphabet, io:
     assert!(length == h.frequencies.len());
     Ok(h)
 }
+
+pub fn read_max_weight_set(path: &str) -> Result<mwis::IndependentSet, io::Error> {
+    let file = File::open(path)?;
+    let mut lines = BufReader::new(file).lines();
+    let line = lines.next().unwrap().unwrap();
+    let length = line.parse().unwrap();
+
+    let mut s = mwis::IndependentSet {
+        length: length,
+        weights: Vec::new(),
+    };
+
+    for line in lines {
+        let line = line?;
+        let weight = line.parse().unwrap();
+        s.weights.push(weight);
+    }
+    assert!(length == s.weights.len());
+    Ok(s)
+}