Submission #1082836

#	Time	Username	Problem	Language	Result	Execution time	Memory
1082836		lamlamlam	Palindrome-Free Numbers (BOI13_numbers)	C++17	100 / 100	1 ms	456 KiB

numbers

#include <bits/stdc++.h>
using namespace std;
#define int long long
#define endl '\n'
int a,b,dp[20][2][11][11][2],n;
string s;
int f(int pos,int tight,int prev1,int prev2,int started)
{
    if(pos==n) return 1;
    if(dp[pos][tight][prev1][prev2][started]!=-1) return dp[pos][tight][prev1][prev2][started];
    int res = 0, ub = 9;
    if(tight) ub = s[pos] - '0';
    for(int i=0; i<=ub; i++){
        if(i==prev1 or i==prev2) continue;
        int is_tight = (tight && i==ub);
        int has_started = (started or i!=0);
        if(has_started) res += f(pos+1,is_tight,i,prev1,has_started);
        else res += f(pos+1,is_tight,10,10,has_started);
    }
    return dp[pos][tight][prev1][prev2][started] = res;
}

int sol(int x)
{
    for(int i=0; i<20; i++)
        for(int j=0; j<11; j++)
            for(int k=0; k<11; k++)
                dp[i][0][j][k][0] = dp[i][0][j][k][1] = dp[i][1][j][k][0] = dp[i][1][j][k][1] = -1;
    s = to_string(x);
    n = s.size();
    return f(0,1,10,10,0);
}

signed main()
{
    ios_base::sync_with_stdio(false);
    cin.tie(NULL);
    #define task "troll"
    if(fopen(task".inp","r")){
        freopen(task".inp","r",stdin);
        freopen(task".out","w",stdout);
    }
    cin >> a >> b;
    cout << sol(b) - sol(a-1);
    cerr << "\nTime: " << clock();
}

Compilation message (stderr)

numbers.cpp: In function 'int main()':
numbers.cpp:40:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   40 |         freopen(task".inp","r",stdin);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~
numbers.cpp:41:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   41 |         freopen(task".out","w",stdout);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~

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