Submission #77206

#	Time	Username	Problem	Language	Result	Execution time	Memory
77206		EntityIT	Palindrome-Free Numbers (BOI13_numbers)	C++14	100 / 100	3 ms	700 KiB

numbers

#include<bits/stdc++.h>

using namespace std;

#define int long long

int a, b, arr[19], dp[19][10][10][2][2];

int calc (int pos, int las1, int las2, bool smaller, bool nonZero) {
    if ( (nonZero || las1) && las1 == las2) return 0;
    if (pos == 1) {
        if (smaller || las1 < arr[pos] || (las1 == arr[pos] && las2 <= arr[pos - 1]) ) return 1;
    }
    int &ret = dp[pos][las1][las2][smaller][nonZero];
    if (ret != -1) return ret;
    ret = 0;
    if (smaller || las1 < arr[pos] || (las1 == arr[pos] && las2 <= arr[pos - 1]) ) {
        for (int las3 = 0; las3 < 10; ++las3) {
            if ( (nonZero || las1) && las1 == las3) continue ;
            ret += calc(pos - 1, las2, las3, max(smaller, (las1 < arr[pos]) ), max(nonZero, (las1 > 0) ) );
        }
    }
    return ret;
}

int solve (int lim) {
    memset(dp, -1, sizeof dp);
    if (lim < 0) return 0;
    int cur = 0;
    memset(arr, 0, sizeof arr);
    while (lim) {
        arr[cur++] = lim % 10; lim /= 10;
    }
    int ret = 0;
    for (int i = 0; i < 10; ++i) {
        for (int j = 0; j < 10; ++j) {
            ret += calc(18, i, j, 0, 0);
        }
    }
    return ret;
}

signed main () {
    ios_base::sync_with_stdio(0); cin.tie(0); cout.tie(0);
    cin >> a >> b;
    cout << solve(b) - solve(a - 1);
    return 0;
}

• Subtask 1: 25 / 25
• Subtask 2: 75 / 75