Armies

function solve(arr) {
  let leaders = [];

  for (let info of arr) {
    if (info.includes('arrives')) {
      const leader = info.substring(0, info.indexOf('arrive') - 1);
      leaders.push([leader, new Map()]);
    } else if (info.includes('defeated')) {
      const leader = info.substring(0, info.indexOf('defeated') - 1);
      if (leaders.filter(x => x[0] === leader).length > 0) { leaders.splice(leaders.indexOf(leaders.filter(x => x[0] === leader)[0]), 1); }
    } else if (info.includes(': ')) {
      const leader = info.substring(0, info.indexOf(':'));
      const army = info.substring(info.indexOf(':') + 2, info.indexOf(','));
      let armyCount = Number(info.substring(info.lastIndexOf(' ')),);
      if (leaders.filter(x => x[0] == leader).length > 0) { leaders.filter(x => x[0] == leader)[0][1].set(army, armyCount); }
    } else if (info.includes('+')) {
      const army = info.substring(0, info.indexOf(' +') );
      const newCount = Number(info.substring(info.indexOf('+') + 1,));
      if (leaders.filter(x => x[1].has(army)).length > 0) {
        let armyToChange = leaders.filter(x => x[1].has(army))[0][1];
        armyToChange.set(army, armyToChange.get(army) + newCount);
      }
    }
  }

  for (let leader of leaders.sort((a, b) => [...b[1].values()].reduce((a, b) => a + b) - [...a[1].values()].reduce((a, b) => a + b))) {
    console.log(`${leader[0]}: ${[...leader[1].values()].reduce((a, b) => a + b)}`);
    [...leader[1].entries()].sort((a, b) => b[1] - a[1]).forEach(x => console.log(`>>> ${x[0]} - ${x[1]}`));
  }
}