projecteuler.net/018/main.rs

use std::fs::File;
use std::io::{ self, BufRead };

struct Tr {
    nums: Vec<Vec<u8>>,
    sums: Vec<Vec<u32>>
}

impl Tr {
    pub fn new() -> Tr {
        let mut nums: Vec<Vec<u8>> = Vec::new();
        let mut sums: Vec<Vec<u32>> = Vec::new();
        let file = File::open("tr.txt").unwrap();
        let lines = io::BufReader::new(file).lines();
        for ln in lines {
            //let sline = ln.split(' ');
            let ns: Vec<u8> = ln.unwrap().split(' ').map(|x| x.parse::<u8>().unwrap()).collect();
            sums.push(vec!(0; ns.len()));
            nums.push(ns);
        }
        return Tr { nums: nums, sums };
    }
    pub fn get(&self, r: usize, c: usize) -> u8 {
        return self.nums[r][c];
    }
    pub fn compute(&mut self) {
        self.sums[0][0] = self.get(0, 0) as u32;
        for c in 1..self.nums.len() {
            for r in 0..self.nums[c].len() {
                let left_top_candidate = if r > 0 { self.sums[c-1][r-1] } else { 0 };
                let right_top_candidate = if r < self.sums[c-1].len() { self.sums[c-1][r] } else { 0 };
                self.sums[c][r] = left_top_candidate.max(right_top_candidate) + self.get(c, r) as u32
            }
        }
    }
    pub fn best_bottom_sum(&self) -> u32 {
        self.sums.last().unwrap().iter().max().unwrap().clone()
    }
}


fn main() {
    let mut tr = Tr::new();
    tr.compute();
    //let n = tr.get(2,2);
    let best_sum = tr.best_bottom_sum();
    println!("best: {}", best_sum);
}