223. Rectangle Area

问题即为求解二个矩阵覆盖区域的总面积：

         S1+S2-S1&S2（二个矩形面积之和-相交区域的面积）

class Solution {
public:
    int computeArea(int A, int B, int C, int D, int E, int F, int G, int H) {
        int total=(C-A)*(D-B)+(G-E)*(H-F), jiao;
        if(C<=E||D<=F||A>=G||B>=H)
            jiao=0;
        else
            jiao=( min(C,G)-max(A,E) )*(min(D,H)-max(B,F));
        return total-jiao;
    }
};