Problem B: Tight words

Input is a sequence of lines, each line contains two integer numbers k and n, 1 <= n <= 100. For each line of input, output the percentage of tight words of length n over the alphabet {0, 1, ... , k} with 5 fractional digits.

Sample input

4 1
2 5
3 5
8 7

Output for the sample input

100.00000
40.74074
17.38281
0.10130

#include <stdio.h>

int main() {
    int k, n;
    while(scanf("%d %d", &k, &n) == 2) {
        double dp[101][10] = {};
        int i, j, l;
        for(i = 0; i <= k; i++)
            dp[1][i] = (double)100/(k+1);
        for(i = 1; i < n; i++) {
            for(j = 0; j <= k; j++) {
                for(l = -1; l <= 1; l++) {
                    if(j+l >= 0 && j+l <= k) {
                        dp[i+1][j+l] += dp[i][j]/(k+1);
                    }
                }
            }
        }
        double ans = 0;
        for(i = 0; i <= k; i++)
            ans += dp[n][i];
        printf("%.5lf\n", ans);
    }
    return 0;
}