use std::iter::repeat;

impl Solution {
    pub fn best_rotation(nums: Vec<i32>) -> i32 {
        let n = nums.len() as i32;
        // cnt : 差分数组
        // cnt最后进行前缀和的加工！
        // 加工完了的cnt[0] :  整体向右移动0的距离, 一共能得多少分
        // 加工完了的cnt[i] :  整体向右移动i的距离, 一共能得多少分
        let mut cnt: Vec<i32> = repeat(0).take((n + 1) as usize).collect();
        for i in 0..n {
            // 遍历每个数！
            // 看看每个数，对差分数组哪些范围，会产生影响!
            if nums[i as usize] < n {
                if i <= nums[i as usize] {
                    Solution::add(&mut cnt, nums[i as usize] - i, n - i - 1);
                } else {
                    Solution::add(&mut cnt, 0, n - i - 1);
                    Solution::add(&mut cnt, n - i + nums[i as usize], n - 1);
                }
            }
        }
        for i in 1..=n {
            cnt[i as usize] += cnt[(i - 1) as usize];
        }
        // 最大得分是啥！已经求出来了
        let mut max = cnt[0];
        let mut ans = 0;
        let mut i = n - 1;
        while i >= 1 {
            // 整体移动的i 0 n-1 n-2 n-3 1
            //         k 0  1   2   3   n-1
            if cnt[i as usize] > max {
                max = cnt[i as usize];
                ans = i;
            }
            i -= 1;
        }
        return if ans == 0 { 0 } else { n - ans };
    }
    fn add(cnt: &mut Vec<i32>, l: i32, r: i32) {
        cnt[l as usize] += 1;
        cnt[(r + 1) as usize] -= 1;
    }
}

fn main() {
    let nums = vec![2, 3, 1, 4, 0];
    let ans = Solution::best_rotation(nums);
    println!("ans = {:?}", ans);
}

struct Solution {}