【SzNOI语法百题】【d042】计算PI

 #include <stdio.h>    int main(int argc,char **argv)  {      float pi=1;      int k,sign = -1;        for(k=1;k<=1000;k++)      {          pi = pi + sign * 1.0 / (2 * k + 1);          sign = -sign;      }            printf("%.4f\n", 4 * pi);      return 0;  }