凸包面积的计算~~~~

stack s; cin>>n; for(i = 0; i < n; i++) cin>>pot[i].x>>pot[i].y; x = pot[0].x; y = pot[0].y; p = 0; for(i = 1; i < n; i++) //寻找最左上的点 { if(pot[i].y < y || (pot[i].y == y && pot[i].x < x)) { x = pot[i].x; y = pot[i].y; p = i; } } p0.x = x; p0.y = y; swap(pot[0