前n项求和

前n项求和

f(n)=1+12+13+14+...+1nf(n) = 1 + \frac{1}{2} + \frac{1}{3} + \frac{1}{4} + ... + \frac{1}{n}f(n)=1+21​+31​+41​+...+n1​

intmain(){intn;inti;doublesum=0.0;scanf("%d",&n);for(i=1;i<=n;i++){sum+=1.0/i;}printf("%f"\n,sum);return0;}

f(n)=1−12+13−14+...1nf(n) = 1 - \frac{1}{2} + \frac{1}{3} - \frac{1}{4} + ... \frac{1}{n}f(n)=1−21​+31​−41​+...n1​

intmain(){intn;inti;doublesum=0.0;intsign=1;scanf("%d",&n);for(i=1;i<=n;i++){sum+=sign*1.0/i;sign=-sign;}printf("交替求和结果是: %f\n",sum);return0;}