二分答案

int binarySearchMin(int lo, int hi) {
    while (lo < hi) {
        int mid = lo + (hi - lo) / 2;
        if (check(mid)) {
            hi = mid;
        } else {
            lo = mid + 1;
        }
    }
    return lo;
}

int binarySearchMax(int lo, int hi) {
    while (lo < hi) {
        int mid = lo + (hi - lo + 1) / 2;
        if (check(mid)) {
            lo = mid;
        } else {
            hi = mid - 1;
        }
    }
    return lo;
}

int splitArray(int[] nums, int m) {
    int lo = 0, hi = 0;
    for (int n : nums) { lo = Math.max(lo, n); hi += n; }
    while (lo < hi) {
        int mid = lo + (hi - lo) / 2;
        if (canSplit(nums, m, mid)) hi = mid;
        else lo = mid + 1;
    }
    return lo;
}

boolean canSplit(int[] nums, int m, int maxSum) {
    int count = 1, curSum = 0;
    for (int n : nums) {
        if (curSum + n > maxSum) {
            count++;
            curSum = n;
            if (count > m) return false;
        } else {
            curSum += n;
        }
    }
    return true;
}

int minEatingSpeed(int[] piles, int h) {
    int lo = 1, hi = Arrays.stream(piles).max().getAsInt();
    while (lo < hi) {
        int mid = lo + (hi - lo) / 2;
        if (canFinish(piles, h, mid)) hi = mid;
        else lo = mid + 1;
    }
    return lo;
}

boolean canFinish(int[] piles, int h, int speed) {
    int hours = 0;
    for (int p : piles) hours += (p + speed - 1) / speed;
    return hours <= h;
}

int shipWithinDays(int[] weights, int days) {
    int lo = 0, hi = 0;
    for (int w : weights) { lo = Math.max(lo, w); hi += w; }
    while (lo < hi) {
        int mid = lo + (hi - lo) / 2;
        if (canShip(weights, days, mid)) hi = mid;
        else lo = mid + 1;
    }
    return lo;
}

double sqrt(double x) {
    double lo = 0, hi = x;
    while (hi - lo > 1e-9) {
        double mid = (lo + hi) / 2;
        if (mid * mid < x) lo = mid;
        else hi = mid;
    }
    return lo;
}