|
| 1 | +/** |
| 2 | + * Title: Sum Game |
| 3 | + * Description: Alice and Bob take turns playing a game, with Alice starting first. |
| 4 | + * Author: Hasibul Islam |
| 5 | + * Date: 06/05/2023 |
| 6 | + */ |
| 7 | + |
| 8 | +/** |
| 9 | + * @param {string} num |
| 10 | + * @return {boolean} |
| 11 | + */ |
| 12 | +var sumGame = function (num) { |
| 13 | + const middle = num.length / 2; |
| 14 | + // < 0 - the sum on the right side is bigger |
| 15 | + // > 0 - the sum on the left side is bigger |
| 16 | + let diff = 0; |
| 17 | + // < 0 - question marks have left on the left side |
| 18 | + // > 0 - question marks have left on the right side |
| 19 | + let turns = 0; |
| 20 | + |
| 21 | + // turns- diff+ help to ensure that the sum on the side with question marks |
| 22 | + // is lower than the other one |
| 23 | + for (let i = 0; i < middle; i += 1) { |
| 24 | + if (num[i] === "?") { |
| 25 | + turns -= 1; |
| 26 | + } else { |
| 27 | + diff += num[i] - "0"; |
| 28 | + } |
| 29 | + } |
| 30 | + |
| 31 | + // counting pure diffs |
| 32 | + for (let i = middle; i < num.length; i += 1) { |
| 33 | + if (num[i] === "?") { |
| 34 | + turns += 1; |
| 35 | + } else { |
| 36 | + diff -= num[i] - "0"; |
| 37 | + } |
| 38 | + } |
| 39 | + |
| 40 | + // Alice wins if the number of turns doesn't allow Bob |
| 41 | + // to keep playing a change by 9 per 2 turns: (Alice-Bob) 0-9 1-8 2-7 3-6 etc, |
| 42 | + // which would reduce the diff of sums to 0 in the end. |
| 43 | + return diff !== turns * 4.5; |
| 44 | +}; |
0 commit comments