#include <stdio.h>
int main()
{
    int a,b,c;
    int v[21][21][21]={0};
    scanf("%d%d%d",&a,&b,&c);
    int i1,i2,i3;
    for(i1=1;i1<=a;i1++)
        for(i2=1;i2<=b;i2++)
            for(i3=1;i3<=c;i3++)
                v[i1][i2][i3]=1;
    int times,time;
    int x1,x2,y1,y2,z1,z2;
    scanf("%d",&times);
    for(time=1;time<=times;time++)
    {
        scanf("%d%d%d%d%d%d",&x1,&y1,&z1,&x2,&y2,&z2);
        for(i1=x1;i1<=x2;i1++)
            for(i2=y1;i2<=y2;i2++)
                for(i3=z1;i3<=z2;i3++)
                    v[i1][i2][i3]=0;
    }
    int sum=0;
    for(i1=1;i1<=a;i1++)
        for(i2=1;i2<=b;i2++)
            for(i3=1;i3<=c;i3++)
                sum+=v[i1][i2][i3];
    printf("%d",sum);
}
//有点小抽象，其他都还好

$\ \ \ \ \ \ \$解释参考注释。

#include <cstdio>

bool cube[21][21][21];//三维立方体空间

int opCutting(int x1, int y1, int z1, int x2, int y2, int z2){
    //切割操作函数
    for(int i = x1; i <= x2; i++){
        for(int j = y1; j <= y2; j++){
            for(int k = z1; k <= z2; k++){
                if(cube[i][j][k]){
                    //如果这部分之前未被切掉（状态为true），则切掉（状态置为false）
                    cube[i][j][k] = false;
                }
            }
        }
    }
    return 0;
}

int opInitCube(int x, int y, int z){
    for(int i = 1; i <= x; i++){
        for(int j = 1; j <= y; j++){
            for(int k = 1; k <= z; k++){
                //初始化未切割立方体，全部状态置为true
                cube[i][j][k] = true;
            }
        }
    }
    return 0;
}

int main(){
    int w, x, h, q, x1, y1, z1, x2, y2, z2, ans = 0;
    scanf("%d %d %d", &w, &x, &h);//读入初始立方体参数
    opInitCube(w, x, h);//初始化立方体
    scanf("%d", &q);//读入操作次数
    for(int _ = 1; _ <= q; _++){//切割，启动！
        scanf("%d %d %d %d %d %d", &x1, &y1, &z1, &x2, &y2, &z2);
        opCutting(x1, y1, z1, x2, y2, z2);
    }
    for(int i = 1; i <= w; i++){
        for(int j = 1; j <= x; j++){
            for(int k = 1; k <= h; k++){
                //计算还有多少未切割的小方块，即状态为true的格子
                if(cube[i][j][k]){
                    ans++;
                }
            }
        }
    }
    printf("%d", ans);
    return 0;
}