UVa 11401

题目不难，书上用的是递推，我这里通过解递推式直接出结果

 

#include <iostream>#include <cstdio>#include <cstring>#include <string>#include <ctime>#include <cmath>#include <vector>#include <deque>#include <algorithm>#include <list>#include <map>#include <set>#include <queue>#include <stack>#define REP(i,n) for(int i=0;i<(n);i++)#define REP1(i,n) for(int i=1;i<=(n);i++)#define FOR(i,a,b) for (int i=(a);i<=(b);i++)#define CLR(x,n) memset(x,n,sizeof(x))#define PN printf("\n")#define read(x) scanf("%d",&x)#define read2(x,y) scanf("%d%d",&x,&y)#define read3(x,y,z) scanf("%d%d%d",&x,&y,&z)#define write(x) printf("%d",x)#define write1(x) printf("%d ",x)#define writeln(x) printf("%d\n",x)#define write2(x,y) printf("%d %d",x,y)#define writeln2(x,y) printf("%d %d\n",x,y)#define write3(x,y,z) printf("%d %d %d",x,y,z)#define writeln3(x,y,z) printf("%d %d %d\n",x,y,z)#define delta 1e-5#define INF 1<<30#define int64 unsigned long longusing namespace std;int main(){    int64 n;    while (scanf("%llu",&n)==1 && n>=3){        n-=3;        int64 l2=n/2;        int64 l1=n-l2;        int64 ans= l1*(l1+1)*(2*l1+1)/6+l2*(l2+1)*(l2+2)/3;        printf("%llu\n",ans);    }    system("pause");    return 0;}