OfferX 矩形和矩陣

題目：48. rotate image

將乙個矩形順時針翻轉90°

class

solution
public
void
reverse
(int
matrix)
}public
void
mirrorrotate
(int
matrix)}}
public
void
swap
(int
matrix,
int i,
int j)
}

解1：使用遞迴實現buildtree, update和sumrange

class

numarray
"tree=%s\n",arrays.tostring(tree));
}public
void
buildtree
(int
nums,
int idx,
int left,
int right)
else
}public
void
update
(int i,
int val)
// update i, from top to bottom
// left,right is the range that idx holds, i is problem being asked
// invariant: left<=i<=right
private
void
updatesub
(int idx,
int left,
int right,
int i,
int diff)
int m = left +
(right-left)/2
;if(i<=m)
else
}public
intsumrange
(int i,
int j)
// invariant: left,right contains i,j
private
intsumrangesub
(int idx,
int left,
int right,
int i,
int j)
// 0 4
// 0,2,4,2
// 3,4,4,4
int m = left +
(right - left)/2
;// sum(i,l,r,x,y)
// i has range l,r, query x,y
// if l,r==x,y return tree[i]
// if l,r intersects x,y
//  [l,m      r]
//     [i,j]
if(melse
if(m>=j)
else}}
/** * your numarray object will be instantiated and called as such:
* numarray obj = new numarray(nums);
* obj.update(i,val);
* int param_2 = obj.sumrange(i,j);
*/

class

numarray
public
void
buildtree
(int
nums,
int idx,
int left,
int right)
public
void
update
(int i,
int val)
private
void
updatesub
(int idx,
int left,
int right,
int i,
int val)
int m = left +
(right-left)/2
;if(i<=m)
else
// important: recompute
tree[idx]
= tree[idx<<1]
+ tree[
(idx<<1)
|1];
}public
intsumrange
(int i,
int j)
// invariant: left,right contains i,j
private
intsumrangesub
(int idx,
int left,
int right,
int i,
int j)
}

tree=

# init added[v]=0 when build tree
update(
int idx,
int l,
int r,
int add)
:if l,r is the range
:          tree[idx]
+=add
....sumrange(
int idx,
int l,
int r)
:return tree[idx]
+ sumrange(left)
+ sumrange(right)

void push(

int v)
:if marked[v]
:        t[v.left]
=t[v.right]
=t[v]
marked[v.left]
=marked[v.right]
=true
marked[v]
=false
get(
int v,
int l,
int r,
int i)
:if l==r:
return t[v]
push(v)
int m =
(l+r)/2
if i<=m:
return get(v.left,l,m,i)
else
return get(v.right,m+
1,r,i)
# 設定值
update(
int v,
int l,
int r,
int i,
int j,
int val)
:if i>j:
return
if(l==i&
&r==j)
:        t[v]
=val
marked[v]
=true
return
push(v)..
.#update sub ranges

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