TOTALODD - Số lẻ hoàn toàn
Tác giả: ladpro98
Ngôn ngữ: C++
#include <bits/stdc++.h>
const int M = 1000006;
using namespace std;
int a[M];
int m;
int main() {
ios :: sync_with_stdio(0);
for(int i = 1; i <= 9; i += 2) a[++m] = i;
int cut = 1;
for(int i = 2; i <= 8; i++) {
int tmp = m;
for(int j = cut; j <= tmp; j++)
for(int k = 1; k <= 9; k += 2)
a[++m] = 10 * a[j] + k;
cut = tmp;
}
string ins; int x;
while (1) {
cin >> ins;
if (ins[1] == 'E') break;
cin >> x;
int j = lower_bound(a + 1, a + 1 + m, x) - a;
int res = a[m] + a[m];
for(int i = 1; i <= j; i++) {
while (j > i && a[i] + a[j - 1] >= x) j--;
if (a[i] + a[j] >= x) res = min(res, a[i] + a[j]);
}
cout << res << endl;
}
return 0;
}