Little Dima and Equation
Posted X_1996
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Little Dima misbehaved during a math lesson a lot and the nasty teacher Mr. Pickles gave him the following problem as a punishment.
Find all integer solutions x (0?<?x?<?109) of the equation:
where a, b, c are some predetermined constant values and function s(x) determines the sum of all digits in the decimal representation of number x.
The teacher gives this problem to Dima for each lesson. He changes only the parameters of the equation: a, b, c. Dima got sick of getting bad marks and he asks you to help him solve this challenging problem.
The first line contains three space-separated integers: a,?b,?c (1?≤?a?≤?5; 1?≤?b?≤?10000; ?-?10000?≤?c?≤?10000).
Print integer n — the number of the solutions that you‘ve found. Next print n integers in the increasing order — the solutions of the given equation. Print only integer solutions that are larger than zero and strictly less than 109.
3 2 8
3
10 2008 13726
1 2 -18
0
2 2 -1
4
1 31 337 967
因为x的范围是0到10的9次方,所以 0<s(x)<=81,
然后就可以枚举s(x)求出x的值,然和求出x的每位上数字之和,
和s(x)比较,看是否满足。
#include<stdio.h> #include<algorithm> #include<iostream> using namespace std; int main() { long long a,b,c; long long s=1; long long t[50000],l=0; long long x; scanf("%I64d %I64d %I64d",&a,&b,&c); for(long long i=1;i<=81;i++) { s=1; for(long long j=1;j<=a;j++) s=s*i; x=b*s; x+=c; long long t1=0; long long t2=x; if(x>0&&x<1000000000) { while(x) { t1+=x%10; x/=10; } if(t1==i) t[l++]=t2; } } sort(t,t+l); printf("%I64d",l); if(l!=0) printf("\n"); for(long long i=0;i<l;i++) { printf("%I64d",t[i]); if(i!=l-1) printf(" "); } return 0; }
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