leetcode 28 rust

题目

代码

pub fn str_str(haystack: String, needle: String) -> i32 {
    let hay_len = haystack.len() as i32;
    let ned_len = needle.len() as i32;
    if hay_len < ned_len {
        return -1;
    }
    if ned_len == 0 {
        return 0;
    }
    for i in 0..(hay_len-ned_len+1) as i32 {
        for j in 0..ned_len as i32 {
            match haystack.chars().nth((i+j) as usize).cmp(&needle.chars().nth((j) as usize)) {
                std::cmp::Ordering::Less | std::cmp::Ordering::Greater => {
                    break;
                },
                std::cmp::Ordering::Equal => {
                    if j == (ned_len-1) {
                        return i;
                    }
                },
            }
        }
    }
    -1
}

测试

#[cfg(test)]
mod tests{
    use super::*;
    #[test]
    fn test_1(){
        assert_eq!(str_str("hello".to_string(),"ll".to_string()),2);
    }
    #[test]
    fn test_2(){
        assert_eq!(str_str("aaaaa".to_string(),"bba".to_string()),-1);
    }
}