1 加到 100 的 时间复杂度 C#.

//1 加到 100 的 时间复杂度:
int n = 100;
int sum = 0;
for(int i = 1; i <= n; i++){
    sum += i;
}
T(1) = 1;    //Initialize 'n'.
T(2) = 1;    //Initialize 'sum'.
T(3) = 1;    //Initialize 'i'.
T(4) = n + 1;    //'i' needs to compared with 'n + 1' times.
T(5) = n;    //'i' increasement times.
T(6) = n;    //'sum' addition times.
T(n) = 1 + 1 + 1 + (n + 1) + n + n = 3*n + 4 = 3*n.

 另外,时间复杂度 T(n) = 3n³ + 5n² = O(n³) -> n -> ∞.