座标离散化(模板)

for(int i=1;i<=n;i++)
  {
    cin >> b[++top] >> b[++top];
    li[i]=b[top-1],ri[i]=b[top];
  }
  sort(b+1,b+1+top);
  top=unique(b+1,b+1+top)-b-1;
  s=0,t=top+1;
  for(int i=1;i<=n;i++)
  {
    int len=ri[i]-li[i];
    li[i]=lower_bound( b+1,b+1+top,li[i] )-b;
    ri[i]=lower_bound( b+1,b+1+top,ri[i] )-b;
  }