Containing-7s-v1.js

function g(n){
    let res = 0;
    for (let i=1; i <= n; i++){
        let temp = i;
        while(temp != 0){
            let digit = temp % 10;
            if(digit == 7){
                res++;
                break;
            }
            temp =  Math.floor(temp / 10);
        }
    }
    return res;
}

g(70); // 8
g(100); // 19 (1*9 + 10) = 19
g(1000); // 271 (19*9 + 100) = 271
g(10000); // 3439 (271*9 + 1000) = 3439