前面全是0的情况特判

#include 
     
      int dp[10][10];int digit[10];int DFS(int pos, int val, int zero, bool limit) {    if (pos == -1) {        return 1;    }    int &now = dp[pos][val];    if (!limit && zero && now != -1) {        return now;    }    int d = limit ? digit[pos] : 9;    int ret = 0;    if (zero == 0) {        for (int i=0; i<=d; ++i) {            ret += DFS (pos - 1, i, i, limit && i == d);        }    } else {        for (int i=0; i<=d; ++i) {            if ((i-val) * (i - val) < 4) {                continue;            }            ret += DFS (pos - 1, i, 1, limit && i == d);        }    }    if (!limit && zero) {        now = ret;    }    return ret;}int solve(int x) {    int n = 0;    while (x) {        digit[n++] = x % 10;        x /= 10;    }    int ret = 0;    return DFS (n - 1, 0, 0, true);}int main() {    memset (dp, -1, sizeof (dp));    int a, b;    while (scanf ("%d%d", &a, &b) == 2) {        printf ("%d\n", solve (b) - solve (a - 1));    }    return 0;}