rust_test/src/main.rs

use std::cmp::max;

struct Solution;
impl Solution {
    pub fn max_free_time(event_time: i32, start_time: Vec<i32>, end_time: Vec<i32>) -> i32 {
        let mut first_selection = 0;
        let mut second_selection = 0;
        let mut third_selection = 0;

        if end_time[end_time.len() - 1] < event_time {
            first_selection = event_time - end_time[end_time.len() - 1];
        }
        let mut last_time = 0;
        for i in 0..start_time.len() {
            if start_time[i] > last_time {
                let val = start_time[i] - last_time;
                if val > first_selection {
                    third_selection = second_selection;
                    second_selection = first_selection;
                    first_selection = val;
                } else if val > second_selection {
                    third_selection = second_selection;
                    second_selection = val;
                } else if val > third_selection {
                    third_selection = val;
                }
            }
            last_time = end_time[i];
        }

        let check_can_add = |left_space: i32, right_space: i32, needed: i32| -> bool {
            if needed <= third_selection {
                return true;
            }
            if needed <= second_selection {
                if left_space  == second_selection && right_space == first_selection ||
                    left_space == first_selection && right_space == second_selection {
                    return false;
                }
                return true;
            }
            if needed <= first_selection {
                if left_space != first_selection && right_space != first_selection {
                    return true;
                }
            }
            return false;
        };
        last_time = end_time[0];
        let mut last = start_time[0];
        let mut ans = start_time[0];
        for i in 1..start_time.len() {
            let left_space = last;
            let right_space = start_time[i] - last_time;
            let new_val = if check_can_add(left_space, right_space, end_time[i - 1] - start_time[i - 1]) {
                left_space + right_space + end_time[i - 1] - start_time[i - 1]
            } else {
                left_space + right_space
            };
            ans = max(ans, new_val);
            last = right_space;
            last_time = end_time[i];
        }
        {
            let left_space = last;
            let right_space = event_time - last_time;
            let new_val = if check_can_add(left_space, right_space, end_time[end_time.len() - 1] - start_time[end_time.len() - 1]) {
                left_space + right_space + end_time[end_time.len() - 1]
                    - start_time[end_time.len() - 1]
            } else {
                left_space + right_space
            };
            ans = max(ans, new_val);
        }
        ans
    }
}

fn main() {
    let sl = Solution::max_free_time(5, vec![1, 3], vec![2, 5]);
    println!("{}", sl);
}