|
| 1 | +packagemedium; |
| 2 | + |
| 3 | +publicclassRangeSumQueryMutable { |
| 4 | + |
| 5 | +publicstaticvoidmain(String...strings){ |
| 6 | +// int[] nums = new int[]{1,3,5}; |
| 7 | + |
| 8 | +int[]nums =newint[]{7,2,7,2,0}; |
| 9 | +NumArraytest =newNumArray(nums); |
| 10 | +test.update(4,6); |
| 11 | +test.update(0,2); |
| 12 | +test.update(0,9); |
| 13 | + } |
| 14 | +} |
| 15 | + |
| 16 | +classNumArray { |
| 17 | +classSegmentTreeNode{ |
| 18 | +SegmentTreeNodeleft; |
| 19 | +SegmentTreeNoderight; |
| 20 | +intstart; |
| 21 | +intend; |
| 22 | +intsum; |
| 23 | + |
| 24 | +publicSegmentTreeNode(intstart,intend){ |
| 25 | +this.start =start; |
| 26 | +this.end =end; |
| 27 | +this.left =null; |
| 28 | +this.right =null; |
| 29 | +this.sum =0; |
| 30 | + } |
| 31 | + } |
| 32 | + |
| 33 | +privateSegmentTreeNoderoot =null; |
| 34 | + |
| 35 | +publicNumArray(int[]nums) { |
| 36 | +root =buildSegmentTree(nums,0,nums.length-1); |
| 37 | + } |
| 38 | + |
| 39 | +SegmentTreeNodebuildSegmentTree(int[]nums,intstart,intend){ |
| 40 | +if(start >end){ |
| 41 | +returnnull; |
| 42 | + }else { |
| 43 | +SegmentTreeNoderoot =newSegmentTreeNode(start,end); |
| 44 | +if(start ==end){ |
| 45 | +root.sum =nums[start]; |
| 46 | + }else { |
| 47 | +intmid =start + (end-start)/2; |
| 48 | +root.left =buildSegmentTree(nums,start,mid); |
| 49 | +root.right =buildSegmentTree(nums,mid+1,end); |
| 50 | +root.sum =root.left.sum +root.right.sum; |
| 51 | + } |
| 52 | +returnroot; |
| 53 | + } |
| 54 | + } |
| 55 | + |
| 56 | +voidupdate(inti,intval) { |
| 57 | +update(root,i,val); |
| 58 | + } |
| 59 | + |
| 60 | +voidupdate(SegmentTreeNoderoot,intpos,intval){ |
| 61 | +if(root.start ==root.end){ |
| 62 | +root.sum =val; |
| 63 | + }else { |
| 64 | +intmid =root.start + (root.end -root.start)/2; |
| 65 | +if(pos <=mid){ |
| 66 | +update(root.left,pos,val); |
| 67 | + }else { |
| 68 | +update(root.right,pos,val); |
| 69 | + } |
| 70 | +root.sum =root.left.sum +root.right.sum; |
| 71 | + } |
| 72 | + } |
| 73 | + |
| 74 | +publicintsumRange(inti,intj) { |
| 75 | +returnsumRange(root,i,j); |
| 76 | + } |
| 77 | + |
| 78 | +intsumRange(SegmentTreeNoderoot,intstart,intend){ |
| 79 | +if(root.end ==end &&root.start ==start){ |
| 80 | +returnroot.sum; |
| 81 | + }else { |
| 82 | +intmid =root.start + (root.end-root.start)/2; |
| 83 | +if(end <=mid){ |
| 84 | +returnsumRange(root.left,start,end); |
| 85 | + }elseif(start >=mid+1){ |
| 86 | +returnsumRange(root.right,start,end); |
| 87 | + }else { |
| 88 | +returnsumRange(root.right,mid+1,end) +sumRange(root.left,start,mid); |
| 89 | + } |
| 90 | + } |
| 91 | + } |
| 92 | +} |
| 93 | + |