Codeforces Round #112 (Div. 2) & #125 (Div. 2)总结(不要用pow&log!!!)
2012-08-05 23:59
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1.遇到需要用大数处理的问题,一定要先去思考能避开大数的程序,不要上来就用c++大数模板或java大数函数,前者敲起来繁琐,后者效率太低。
2.pow,log这种处理double的东西尽量不要和整型运算混用,会造成精度缺失以导致wa的。
3.遇到不等关系,为了防止精度缺失,最好还是一步一步踏踏实实地运算。
#include <stdio.h> #include <iostream> using namespace std; int main() { long long k,b,n,t,z; while(cin >> k >> b >> n >>t){ long long x=1; int cou=0; while(x<=t && cou<=n){ x=k*x+b; cou++; } cout << n-cou+1 <<endl; } return 0; }
2.pow,log这种处理double的东西尽量不要和整型运算混用,会造成精度缺失以导致wa的。
3.遇到不等关系,为了防止精度缺失,最好还是一步一步踏踏实实地运算。
#include <iostream> #include <math.h> using namespace std; #include <stdio.h> int main() { //freopen("in.txt","r",stdin); //freopen("WA.txt","w",stdout); int n; double k; while(cin >> n >>k){ int l=1,r=n; int mid=-1; while(l<r){ //cout << l <<" "<< r <<endl; mid=(l+r)/2; long long p=0; long long kk=1; while(mid>=kk){ kk*=k; p++; } long long sum=0; for(int i=0;i<=p;i++){ kk=1; for(int j=0;j<i;j++){ kk*=k; } sum+=mid/kk; } if(sum>=n) r=mid; else l=mid+1; } cout << r <<endl; } return 0; }
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