rust_test/src/main.rs

struct Solution;
impl Solution {
    pub fn first_missing_positive(mut nums: Vec<i32>) -> i32 {
        for i in 0..nums.len(){
            if nums[i] <= 0 || nums[i] > nums.len() as i32 {
                continue;
            }
            let mut temp = nums[i];
            nums[i] = -1;
            while temp > 0 && temp <= nums.len() as i32 {
                let temp2 = nums[temp as usize - 1];
                nums[temp as usize - 1] = temp;
                if temp == temp2 {
                    break;
                }
                temp = temp2;
            }
        }
        println!("{:?}", nums);
        for i in 0..nums.len(){
            if nums[i] != (i as i32 + 1) {
                return i as i32 + 1;
            }
        }
        nums.len() as i32 + 1
    }
}

fn main() {
    let sl = Solution::first_missing_positive(vec![1]);
    println!("{:?}", sl);
}