function lowBit(n) {
    return n & -n;
}
export class FinweckTree {
    /**
     * @param l length of the array
     * @param min min value of the array
     */
    constructor(l, min) {
        this.l = l;
        this.min = min;
        const ft = new Array(l + 1);
        for (let i = 0; i < l + 1; ++i) {
            ft[i] = 0;
        }
        this.ft = ft;
    }
    /**
     * Add arr[i] by n, start from 0
     * @param i the index of the element to be added
     * @param n the value to be added
     */
    add(i, n) {
        if (n === 0)
            return;
        const { l, ft } = this;
        i += 1;
        while (i <= l) {
            ft[i] += n;
            i += lowBit(i);
        }
    }
    /**
     * Get the value of index i
     * @param i index
     * @returns value of the index
     */
    get(i) {
        return this.sum(i + 1) - this.sum(i);
    }
    /**
     * Get the sum of first i elements
     * @param i count of head elements to be added
     * @returns the sum of first i elements
     */
    sum(i) {
        if (i === undefined)
            i = this.l;
        if (i <= 0)
            return 0;
        const { ft, min, l } = this;
        if (i > l)
            throw new Error('[FinweckTree.sum]: `i` is larger than length.');
        let ret = i * min;
        while (i > 0) {
            ret += ft[i];
            i -= lowBit(i);
        }
        return ret;
    }
    /**
     * Get the largest count of head elements whose sum are <= threshold
     * @param threshold
     * @returns the largest count of head elements whose sum are <= threshold
     */
    getBound(threshold) {
        let l = 0;
        let r = this.l;
        while (r > l) {
            const m = Math.floor((l + r) / 2);
            const sumM = this.sum(m);
            if (sumM > threshold) {
                r = m;
                continue;
            }
            else if (sumM < threshold) {
                if (l === m) {
                    if (this.sum(l + 1) <= threshold)
                        return l + 1;
                    return m;
                }
                l = m;
            }
            else {
                return m;
            }
        }
        return l;
    }
}