Old Top Coder riddle: Making a number by inserting +

Question

I am thinking about this topcoder problem.

Given a string of digits, find the minimum number of additions required for the string to equal some target n

Answer 1

dynamic programming :

public class QuickSums {

public static int req(int n, int[] digits, int sum) {

    if (n == 0) {
        if (sum == 0)
            return 0;
        else
            return -1;
    } else if (n == 1) {
        if (sum == digits[0]) {
            return 0;
        } else {
            return -1;
        }
    }

    int deg = 1;
    int red = 0;

    int opt = 100000;
    int split = -1;

    for (int i=0; i