用矢量计算：

class Solution {
public:bool checkOverlap(int radius, int xCenter, int yCenter, int x1, int y1, int x2, int y2) {//矩形中心float Tx=(float)(x1+x2)/2;float Ty=(float)(y1+y2)/2;//强行进行对称操作，只考虑第一象限if(xCenter<Tx){xCenter=2*Tx-xCenter;}if(yCenter<Ty){yCenter=2*Ty-yCenter;}//圆心到对角顶点的距离int rDTx=xCenter-x2;int rDTy=yCenter-y2;//四种情况if(rDTx>0&&rDTy>0){return rDTx*rDTx+rDTy*rDTy<=radius*radius;}else if(rDTx<=0&&rDTy>0){return rDTy<=radius;}else if(rDTy<=0&&rDTx>0){return rDTx<=radius;}else if(rDTx<=0&&rDTy<=0){return true;}return false;}
};