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

求两个矩形组成的总面积，每个矩形给出了左下角坐标和右上角坐标。
如图，左边矩形的面积是 24，右边矩形的面积是 27，两矩形的交集面积是 6，所以总面积是 24+27-6=45

int computeArea(int A, int B, int C, int D, int E, int F, int G, int H) {
    // 代码
}

想到一个代码，不过各种if、else嵌套，不敢拿出来献丑

这个是不是要从几何学角度解决

哈哈，被看透了

#include <stdio.h>

#define MAX(a, b) ((a) > (b) ? (a) : (b))
#define MIN(a, b) ((a) < (b) ? (a) : (b))

int computeArea(int A, int B, int C, int D, int E, int F, int G, int H)
{
    int left   = MAX(A, E);
    int bottom = MAX(B, F);
    int right  = MIN(C, G);
    int top    = MIN(D, H);
    return (C - A) * (D - B) + (G - E) * (H - F) - MAX(right - left, 0) * MAX(top - bottom, 0);
}

int main(void)
{
    printf("%d\n", computeArea(-3, 0, 3, 4, 0, -1, 9, 2));
    return 0;
}

[ 本帖最后由 kenierlee 于 2015-8-7 11:43 编辑 ]

如果没有重叠部分呢？

感谢兄台指点，已更正

#include<stdio.h>
#include<math.h>
int computeArea(int a,int b,int c,int d,int e,int f,int g,int h)
{
    int area,s1,s2,s3;
    s1=(c-a)*(d-b);
    s2=(g-e)*(h-f);
    int max1,max2;
    max1=(g>c?g:c)-(a<e?a:e);
    max2=(h>d?h:d)-(f<b?f:b);    
    if(c-a+g-e>max1&&d-b+h-f>max2)//两矩形相交
    {
    s3=(c-a+g-e-max1)*(d-b+h-f-max2);//相交矩形面积
    area=s1+s2-s3;
    }
    else
        area=s1+s2;
    return area;
}
int main()
{
    int a,b,c,d,e,f,g,h;
    int area;
    scanf("%d%d%d%d%d%d%d%d",&a,&b,&c,&d,&e,&f,&g,&h);
    area=computeArea(a,b,c,d,e,f,g,h);
    printf("%d",area);
  return 0;
}

#include<stdio.h>

int abss(int a, int b){
    if(a > b){
        return a - b;
    }
    return b - a;
}

double computeArea(int A, int B, int C, int D, int E, int F, int G, int H) {
    double totalArea, area1, area2;
    area1 = (C - A) * (D - B);
    area2 = (G - E) * (H - F);
    printf("area1 = %f\narea2 = %f\n", area1, area2);
    totalArea = area1 + area2;
    //根据重心位置和长宽判断是否相交
    int center_x = abss(A + C, E + G),
        center_y = abss(B + D, F + H),
        length_x = C - A + G - E,
        length_y = D - B + H - F;
    if(center_x < length_x && center_y < length_y){
        double cross = (length_x - center_x) * (length_y - center_y) / 4;
        printf("cross = %f\n", cross);
        totalArea -= cross;
    }
    return totalArea;
}

int main(){
    printf("area = %f", computeArea(-3,0,3,4,0,-1,9,2));
    return 0;
}