+typedef struct {
+ IV n, m;
+ IV* t;
+} bit2d;
+
+bit2d* bit2d_create(IV n, IV m) {
+ if(n < 1 || m < 1){
+ croak("A dimension is less than 1");
+ return 0;
+ }
+ n++, m++;
+ bit2d *ret;
+ Newx(ret, 1, bit2d);
+ ret->n = n;
+ ret->m = m;
+ Newxz(ret->t, n * m, IV);
+ return ret;
+}
+
+void bit2d_free(bit2d *b) {
+ Safefree(b->t);
+ Safefree(b);
+}
+
+IV bit2d_query(bit2d *b, IV i1, IV i2) {
+ if(i1 > b->n || i1 < 1) {
+ croak("Index 1 not in range [1," IVdf "]", b->n);
+ return 0;
+ }
+ if(i2 > b->m || i2 < 1) {
+ croak("Index 2 not in range [1," IVdf "]", b->m);
+ return 0;
+ }
+ IV ret = 0, i2c = i2;
+ while(i1) {
+ i2 = i2c;
+ while(i2)
+ ret += b->t[i1 * b->n + i2], i2 -= i2 & -i2;
+ i1 -= i1 & -i1;
+ }
+ return ret;
+}
+
+void bit2d_update(bit2d *b, IV i1, IV i2, IV value) {
+ if(i1 > b->n || i1 < 1) {
+ croak("Index 1 not in range [1," IVdf "]", b->n);
+ return;
+ }
+ if(i2 > b->m || i2 < 1) {
+ croak("Index 2 not in range [1," IVdf "]", b->m);
+ return;
+ }
+ IV i2c = i2;
+ while(i1 < b->n) {
+ i2 = i2c;
+ while(i2 < b->m)
+ b->t[i1 * b->n + i2] += value, i2 += i2 & -i2;
+ i1 += i1 & -i1;
+ }
+}
+
+void bit2d_clear(bit2d *b) {
+ Zero(b->t, b->n * b->m, IV);
+}
+