力扣1401. 圆和矩形是否有重叠

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;
    }
};