原题链接：蓝桥杯算法提高VIP-函数求值
解题思路:
注意事项:
参考代码:
#include <iostream>
#include <cstdio>
#include <cstring>
#include <vector>
using namespace std;
const int N = 105, mod = 20123;
char str[N];
int get(vector<int> &numbers, int l, int r)
{
vector<int> dividend;
for (int i = r; i >= l; --i) dividend.push_back(numbers[i]);
int t = 0;
for (int i = dividend.size()-1; i >= 0; --i)
{
dividend[i] += t * 10;
t = dividend[i] % mod;
dividend[i] /= mod;
while (dividend.size() && !dividend.back()) dividend.pop_back();
}
return t;
}
int expmod(int a, int b)
{
int res = 1;
while (b)
{
if (b & 1) res = (res * a) % mod;
a = (a * a) % mod;
b >>= 1;
}
return res;
}
int dp(int u)
{
int n = strlen(str);
vector<int> numbers;
for (int i = 0; i < n; ++i) numbers.push_back(str[i]-'0');
int res = 0;
for (int i = 0; i < n; ++i)
{
if (i) res = (res + get(numbers, 0, i-1) * expmod(10, n-i-1)) % mod;
if (numbers[i] == u) res = (res + get(numbers, i+1, n-1) + 1) % mod;
else if (numbers[i] > u) res = (res + expmod(10, n-i-1)) % mod;
}
return res;
}
int main()
{
scanf("%s", str);
printf("%d", (dp(1) + dp(2)) % mod);
return 0;
}0.0分
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