UVA 11361 - Investigating Div-Sum Property（数位DP）

#include <stdio.h>
#include <string.h>

int t, a, b, k, f[15][105][105], n, d[15];

void tra(int num) {
	n = 0;
	while (num) {
		d[++n] = num % 10;
		num /= 10;
	}
	for (int i = 1; i <= n / 2; i++) {
		int t = d[i];
		d[i] = d[n + 1 - i];
		d[n + 1 - i] = t;
	}
}

int solve(int num) {
	if (num == 0) return 1;
	tra(num);
	memset(f, 0, sizeof(f));
	int x1 = 0, x2 = 0;
	for (int i = 1; i <= n; i++) {
		for (int x = 0; x < k; x++) {
			for (int y = 0; y < k; y++) {
				for (int j = 0; j <= 9; j++) {
					f[i][(x * 10 + j) % k][(y + j) % k] += f[i - 1][x][y];
				}
			}
		}
		for (int j = 0; j < d[i]; j++)
			f[i][(x1 * 10 + j) % k][(x2 + j) % k]++;
		x1 = (x1 * 10 + d[i]) % k;
		x2 = (x2 + d[i]) % k;
	}
	if (x1 == 0 && x2 == 0)
		f[n][0][0]++;
	return f[n][0][0];
}

int main() {
	scanf("%d", &t);
	while (t--) {
		scanf("%d%d%d", &a, &b, &k);
		if (k > 100) printf("0\n");
		else printf("%d\n", solve(b) - solve(a - 1));
	}
	return 0;
}