You are an expert in writing code in many different languages. Your goal is to perform code completion for the following code, keeping in mind the rest of the code and the file meta data.
    Metadata details:
    filename: solver.rs
    path of file: ./repos/rustrogueliketutorial/chapter-62-magicitems/src/map_builders/waveform_collapse
    
    the code of the file until where you have to start completion: use super::{MapChunk, Map};
use std::collections::HashSet;

pub struct Solver {
    constraints: Vec<MapChunk>,
    chunk_size : i32,
    chunks : Vec<Option<usize>>,
    chunks_x : usize,
    chunks_y : usize,
    remaining : Vec<(usize, i32)>, // (index, # neighbors)
    pub possible: bool
}

impl Solver {
    pub fn new(constraints: V
    
    pub fn new(constraints: Vec<MapChunk>, chunk_size: i32, map : &Map) -> Solver {
        let chunks_x = (map.width / chunk_size) as usize;
        let chunks_y = (map.height / chunk_size) as usize;
        let mut remaining : Vec<(usize, i32)> = Vec::new();
        for i in 0..(chunks_x*chunks_y) {
            remaining.push((i, 0));
        }

        Solver {
            constraints,
            chunk_size,
            chunks: vec![None; chunks_x * chunks_y],
            chunks_x,
            chunks_y,
            remaining,
            possible: true
        }
    }