hdu 4734 F(x)(数位dp)

#include <cstdio>
#include <cstring>
#include <algorithm>

using namespace std;
const int maxn = 10000;

int n, bit[15];
int dp[15][maxn];

int init () {
int s = n = 0, a, b;
scanf("%d%d", &a, &b);

for (int i = 0; a; i++) {
s += (a % 10) * (1<<i);
a /= 10;
}

while (b) {
bit[n++] = b % 10;
b /= 10;
}
return s;
}

int dfs (int d, int s, int flag) {

if (d == -1)
return (s >= 0);

if (flag == 0 && dp[d][s] != -1)
return dp[d][s];

int ret = 0, end = (flag ? bit[d] : 9);
for (int i = 0; i <= end; i++) {
if (s < i * (1<<d))
continue;
ret += dfs(d - 1, s - i * (1<<d), flag && i == end);
}

if (flag == 0)
dp[d][s] = ret;
return ret;
}

int main () {
int cas;
scanf("%d", &cas);
memset(dp, -1, sizeof(dp));
for (int kcas = 1; kcas <= cas; kcas++) {
int f = init();
printf("Case #%d: %d\n", kcas, dfs(n - 1, f, 1));
}
return 0;
}