摘要：#include<stdio.h>int main( ){ int n; int x[3]; int y[3]; double s; while( scanf("%d",&n) == 1 ) { if ( n == 0 ) { break; } if( n >= 3 && n <= 100 ) { s = 0; scanf("%d %d",&x[0],&y[0]); x[2] = x[0]; y[2] = y[0]; while( --n ) { scanf("%d %d" 阅读全文