0746-min-cost-climbing-stairs.rs

//  time compexity : O(n)
// space compexity : O(1)

impl Solution {
    pub fn min_cost_climbing_stairs(mut cost: Vec<i32>) -> i32 {
        for i in 2..cost.len(){
            cost[i] += cost[i- 1].min(cost[i-2]);
        }
        
        let len = cost.len();
        
        cost[len - 1].min(cost[len - 2])
    }
}