《leetCode》：Rectangle Area

題目

Find the total area covered by two rectilinear rectangles in a 2D plane.

Each rectangle is defined by its bottom left corner and top right corner as shown in the figure.

Rectangle Area

Assume that the total area is never beyond the maximum possible value of int.

思路

此題比較簡單，當兩個矩形有交集時，則結果就是兩個矩形的面積減去兩個矩形的交集。如果兩個矩形沒有交集，則就是兩個矩形的面積之和。 判斷有無交集隻需要判斷四種情況（在上面、下面、左邊、右邊；其中包括了在左上方呀右上方呀左下方呀右下方）即可。

int max(int a,int b){
    return a>b?a:b;
}
int min(int a,int b){
    return a<b?a:b;
}
int computeArea(int A, int B, int C, int D, int E, int F, int G, int H) {
    if(C<A||D<B||G<E||H<F){//矩形有效性檢查 
        return ;
    } 
    int twoRectArea=(C-A)*(D-B)+(G-E)*(H-F);
    int x0=max(A,E);
    int y0=max(B,F);
    int x1=min(C,G);
    int y1=min(D,H);
    int intersectArea=(x1-x0)*(y1-y0);  
    if(C<=E||D<=F||G<=A||H<=B){//沒有交集 
        return  twoRectArea;
    }   
    else{
        return twoRectArea-intersectArea; 
    }

}