adventofcode2022/day12/solution.ts

import { readFileSync } from 'fs';
import { join } from 'path';

const fileString = readFileSync(join(__dirname, "input"), 'utf-8');
var rows = fileString.split("\n");

rows = rows.map(val => {
  return val.trim();
});

rows = rows.filter(val => {
  return val.length > 0;
});

const grid = rows.map(val => {
  return val.split("");
})

var targetPos = [0,0];
for (var i = 0; i < grid.length; i++) {
  for (var j = 0; j < grid[i].length; j++) {
    if (grid[i][j] == "E") {
      console.log("target set", i, j);
      targetPos = [i, j];
      grid[i][j] = "z";
    }
    if (grid[i][j] == "S") {
      grid[i][j] = "a";
    }
  }
}


// Build Graph
var graph: {} = {};
for (var i = 0; i < grid.length; i++) {
  for (var j = 0; j < grid[i].length; j++) {
    const idx = JSON.stringify([i, j])
    const height = grid[i][j].charCodeAt(0);
    graph[idx] = {
      "value": height,
      "next": {}
    };
    if (!((i - 1) < 0)) {
      if ((grid[i - 1][j].charCodeAt(0) - height <= 1) && (grid[i - 1][j].charCodeAt(0) - height >= -1)) {
        const nidx = JSON.stringify([i - 1, j])
        graph[idx]["next"][nidx] = 1;
      }
    }
    if (!((i + 1) >= grid.length)) {
      if ((grid[i + 1][j].charCodeAt(0) - height <= 1) && (grid[i + 1][j].charCodeAt(0) - height >= -1)) {
        const nidx = JSON.stringify([i + 1, j])
        graph[idx]["next"][nidx] = 1;
      }
    }
    if (!((j - 1) < 0)) {
      if ((grid[i][j - 1].charCodeAt(0) - height <= 1) && (grid[i][j - 1].charCodeAt(0) - height >= -1)) {
        const nidx = JSON.stringify([i, j - 1])
        graph[idx]["next"][nidx] = 1;
      }
    }
    if (!((j + 1) >= grid[i].length)) {
      if ((grid[i][j + 1].charCodeAt(0) - height <= 1) && (grid[i][j + 1].charCodeAt(0) - height >= -1)) {
        const nidx = JSON.stringify([i, j + 1])
        graph[idx]["next"][nidx] = 1;
      }
    }
  }
}

function closestNode(distances: {}, visited) {
  var shortest = null;
  for (const node in distances) {
    var curentShortest = shortest === null || distances[node] < distances[shortest];
    if (curentShortest && !visited.includes(node)) {
      shortest = node;
    }
  }
  return shortest;
}

function findShortestPath(g:{}, startN: string, endN: string) {
  var distances = {};
  distances[endN] = Infinity;
  distances = Object.assign(distances, g[startN]["next"]);

  var parents = {endN: null};
  for (const neighbor in g[startN]["next"]) {
    parents[neighbor] = startN;
  }

  var visited = [];
  var node = closestNode(distances, visited);
  while (node) {
    var distance = distances[node];
    var children = g[node]["next"];
    for (const child in children) {
      if (child === startN) {
        continue;
      } else {
        var newDistance = distance + children[child];
        if (!distances[child] || distances[child] > newDistance) {
          distances[child] = newDistance;
          parents[child] = node;
        }
      }
    }
    visited.push(node);
    node = closestNode(distances, visited);
  }
  var shortestPath = [endN];
  var parent = parents[endN];
  while (parent) {
    shortestPath.push(parent);
    parent = parents[parent];
  }
  shortestPath.reverse();
  return {d: distances[endN], s: shortestPath, dd: distances}
}
const res = findShortestPath(graph, JSON.stringify([0,0]), JSON.stringify(targetPos))
console.log(res["dd"], res["d"]);