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Create 2742-painting-the-walls.js #3979

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27 changes: 27 additions & 0 deletions javascript/2742-painting-the-walls.js
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/**
* DP | Memoization
* Time O(n^2) | Space O(n^2)
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Can optimize space

/**
 * DP - Bottom Up
 * Array - Tabulation
 * Time O(N^2) | Space O(N)
 * @param {number[]} cost
 * @param {number[]} time
 * @return {number}
 */
var paintWalls = (cost, time) => {
    const tabu = initTabu(cost);

    for (let i = 0; (i < cost.length); i++) {
        for (let remain = cost.length; (0 < remain); remain--) {
            const left = tabu[Math.max(((remain - 1) - time[i]), 0)] + cost[i];
            const right = tabu[remain];

            tabu[remain] = Math.min(left, right);
        }
    }

    return tabu[cost.length];
}

var initTabu = ({ length }) => {
    const tabu = new Array(length + 1).fill(Number.MAX_SAFE_INTEGER);

    tabu[0] = 0;

    return tabu;
}

* https://leetcode.com/problems/painting-the-walls/
* @param {number[]} cost
* @param {number[]} time
* @return {number}
*/
var paintWalls = function(cost, time) {

const cache = new Map();

const dfs = (i, remaining) => {

const hash = `${i},${remaining}`;

if (cache.has(hash)) return cache.get(hash);
if (remaining <= 0) return 0;
if (i === cost.length) return Infinity;

const res = Math.min(cost[i] + dfs(i+1, remaining - 1 - time[i]), dfs(i+1, remaining));
cache.set(hash, res);
return res;
}

return dfs(0, time.length);
};