307. Range Sum query-mutable

/** 307. Range Sum query-mutable * 2016-7-3 by Mingyang * Insane segment Tree, no words anymore*/classNumarray {classSegmenttreenode {intstart, end;        Segmenttreenode left, right; intsum;  PublicSegmenttreenode (intStartintend) {             This. Start =start;  This. end =end;  This. left =NULL;  This. right =NULL;  This. Sum = 0; }} Segmenttreenode Root=NULL;  PublicNumarray (int[] nums) {Root= Buildtree (nums, 0, Nums.length-1); }    PrivateSegmenttreenode Buildtree (int[] Nums,intStartintend) {        if(Start >end) {            return NULL; } Else{segmenttreenode ret=NewSegmenttreenode (start, end); if(Start = =end) {Ret.sum=Nums[start]; } Else {                intMID = start + (End-start)/2; Ret.left=Buildtree (Nums, start, mid); Ret.right= Buildtree (Nums, Mid + 1, end); Ret.sum= Ret.left.sum +ret.right.sum; }                     returnret; }    }       voidUpdateintIintval)    {Update (root, I, Val); }       voidUpdate (Segmenttreenode root,intPosintval) {        if(Root.start = =root.end) {root.sum=Val; } Else {            intMID = Root.start + (Root.end-root.start)/2; if(Pos <=mid) {Update (Root.left, POS, Val); } Else{update (Root.right, POS, Val); } root.sum= Root.left.sum +root.right.sum; }    }     Public intSumrange (intIintj) {returnSumrange (Root, I, j); }         Public intSumrange (Segmenttreenode root,intStartintend) {        if(Root.end = = End && Root.start = =start) {            returnroot.sum; } Else {            intMID = Root.start + (Root.end-root.start)/2; if(End <=mid) {returnSumrange (Root.left, start, end); } Else if(Start >= mid+1) {                returnSumrange (root.right, start, end); }  Else {                    returnSumrange (Root.right, mid+1, end) +Sumrange (Root.left, start, mid); }        }    }}

307. Range Sum query-mutable