问转换一个三角形，并用C++对它们排序

EN

#include<stdio.h>
#include<stdlib.h>
#include<math.h>
typedef struct{
float x;
float y; }point;
typedef struct {
point a;
point b;
point c; }triangle;

      float angle(triangle *t,int i){

float a,b,c,alpha;
 a=(t[i].b.x-t[i].c.x)*(t[i].b.x-t[i].c.x)+(t[i].b.y-t[i].c.y)*(t[i].b.y-t[i].c.y);
 b=(t[i].a.x-t[i].b.x)*(t[i].a.x-t[i].b.x)+(t[i].a.y-t[i].b.y)*(t[i].a.y-t[i].b.y);
   c=(t[i].a.x-t[i].c.x)*(t[i].a.x-t[i].c.x)+(t[i].a.y-t[i].c.y)*(t[i].a.y-t[i].c.y);
  alpha=acos((b*b+c*c-a*a)/(2*b*c));
 return alpha;} 

   void move(int r,float angle,triangle *t,int i){

float alpha;
 // rotation
     alpha=angle*M_PI/180;
        t[i+1].a.x=t[i].a.x*cos(alpha)-t[i].a.y*sin(alpha);
        t[i+1].a.y=t[i].a.x*sin(alpha)+t[i].a.y*cos(alpha);
    t[i+1].b.x=t[i].b.x*cos(alpha)-t[i].b.y*sin(alpha);
    t[i+1].b.y=t[i].b.x*sin(alpha)+t[i].b.y*cos(alpha);
    t[i+1].c.x=t[i].c.x*cos(alpha)-t[i].c.y*sin(alpha);
    t[i+1].c.y=t[i].c.x*sin(alpha)+t[i].c.y*cos(alpha);

// homotecy
    t[i+1].a.x=t[i+1].a.x*r;
    t[i+1].a.y=t[i+1].a.y*r;
    t[i+1].b.x=t[i+1].b.x*r;
    t[i+1].b.y=t[i+1].b.y*r;
    t[i+1].c.x=t[i+1].c.x*r;
     t[i+1].c.y=t[i+1].c.y*r;
       return;}

void sort(triangle *t,int n){

float a,b;
int k,i;
for(i=1;i<=n-1;i++){
    a=angle(t,i);
    k=i-1;
    b=angle(t,k);
    while(a>=0 && a<=(M_PI*2) && b>a){
        t[k+1]=t[k];
        k--;
    }
    t[k+1]=t[i];
}
return;}

 int main(void){

triangle *t;
float angle;
int r,n,i;
char so[50];
FILE *s;

printf("n?\n");
scanf("%d",&n);
printf("r?\n");
scanf("%d",&r);
printf("angle?\n");
scanf("%f",&angle);
t=(triangle*)malloc((n+1)*sizeof(point));
if(t==NULL) exit(1);
printf("Triangle?\n");
scanf("%f %f %f %f %f %f",&t[0].a.x,&t[0].a.y,&t[0].b.x,&t[0].b.y,&t[0].c.x,&t[0].c.y);
for(i=0;i<n;i++){
    move(r,angle,t,i);
    sort(t,n);
}
printf("file?\n");
scanf("%s",so);
s=fopen(so,"w");
if(s==NULL) exit(1);
for(i=0;i<n;i++){
    fprintf(s,"%9.5f %9.5f %19.5f %9.5f %9.5f %9.5f\n",t[i].a.x,t[i].a.y,t[i].b.x,t[i].b.y,t[i].c.x,t[i].c.y);
}
fclose(s);  
free(t);
   return 0;}

free(): invalid next size (normal)