Rust 1..100 累加求和

// 循环实现
fn sum(n:i32)->i32{
   let mut sum:i32=0;
   for i in 0..=100{
     sum +=i;
   }
   sum
}


>>> println!("{}",sum(100));

// 递归实现
fn sum_by_recursion(n:usize)->usize{
   if n==0{
      0
   }
   else{
      n+sum_by_recursion(n-1)
   }


let sum=sum_by_recursion(100)
println!("sum:{}",sum) 
// >>> 5050