在leetcode上做题，发现编译不过，提示类型不匹配。请问怎么把usize转换成i32，或者有其它的解决办法？万分感谢！

代码：

impl Solution {
    pub fn two_sum(nums: Vec<i32>, target: i32) -> Vec<i32> {
        let mut finder: i32;
        let mut indices = Vec::new();
        for (i, i_v) in nums.iter().enumerate() {
            finder = target - i_v;
            for (j, j_v) in nums.iter().enumerate() {
                if j_v == &finder && j != i {
                    indices.push(i);
                    indices.push(j);
                    break;
                }
            }
        }
        indices
    }
}

报错信息：

mismatched types

expected i32, found usize

note: expected type `std::vec::Vec<i32>`
         found type `std::vec::Vec<usize>`