solution.ts

function candy (ratings: number[]): number {
    const left:number[] = new Array(ratings.length);
    for (let i = 0; i < ratings.length; i++) {
        if (i > 0 && ratings[i] > ratings[i - 1]) {
            left[i] = left[i - 1] + 1;
        } else {
            left[i] = 1;
        }
    }
    let result = 0;
    let right = 0;
    for (let i = ratings.length - 1; i > -1; i--) {
        if (i < ratings.length - 1 && ratings[i + 1] < ratings[i]) {
            right++;
        } else {
            right = 1;
        }
        result += Math.max(right, left[i]);
    }
    return result;
}