#include "head.h"struct Node * CreateNodesetV(int number,char opr,int type)
{struct nodeData db;db.numberValue=number;db.operatorValue=opr;db.symbolType=type;struct Node * myNode=malloc(sizeof(struct Node));CreateNode(db,myNode);return myNode;
};void  CreateNode(struct nodeData nd,struct Node * myN)
{myN->NData.numberValue=nd.numberValue;myN->NData.operatorValue=nd.operatorValue;myN->NData.symbolType=nd.symbolType;myN->lchilden='\0';myN->rchilden='\0';
};char insertNode(struct Node * myNode,struct Node * father,char lr)
{char result='Y';if(lr=='L'){if(father->lchilden=='\0'){father->lchilden=myNode;}else{result='N';}}else{if(father->rchilden=='\0'){father->rchilden=myNode;}else{result='N';}}return result;
}//原来树的遍历也就是递归.我去,我说自己怎么老是不得要领.根源在于没想明白递归函数.
void visitTree(struct Node * Root)
{if(Root->lchilden!='\0'){visitTree(Root->lchilden);}else{//终止递归的确定事件,是无事件.
    }if(Root->NData.symbolType==1){printf("%d",Root->NData.numberValue);}else{printf("%c",Root->NData.operatorValue);}if(Root->rchilden!='\0'){visitTree(Root->rchilden);}else{//终止递归的确定事件,是无事件.
    }
}

//所以如果用递归来做运算必须是后序遍历，要等左右树都有结果了，才用符号。
//其实我们的心算和笔算，也是后续遍历。int visitTree_2(struct Node * Root)
{int lvalue;int rvalue;int result;if(Root->lchilden!='\0'){lvalue=visitTree_2(Root->lchilden);}else{return Root->NData.numberValue;}if(Root->rchilden!='\0'){rvalue=visitTree_2(Root->rchilden);}else{return Root->NData.numberValue;}switch (Root->NData.operatorValue){case '+':{result=lvalue+rvalue;break;}case '-':{result=lvalue-rvalue;break;}case '*':{result=lvalue*rvalue;break;}case '/':{result=lvalue/rvalue;break;}}return result;
}

//treestruct nodeData
{int symbolType; //1: number 2: operatorint numberValue;char operatorValue;
};struct Node
{struct nodeData NData;struct Node * lchilden;struct Node * rchilden;
};char insertNode(struct Node * myNode,struct Node * father,char lr);
struct Node * CreateNodesetV(int number,char opr,int type);
void  CreateNode(struct nodeData nd,struct Node * myN);
void visitTree(struct Node * Root);

int main()
{char * expression="2+3*5-4/2";//每次取一个数字和操作符，对比操作符和之前操作符的优先顺序。//状1，大于，则符号为之前树的右子树，数字为符号的左子树。//状2，小于，则数字为之前树的右字树，之前树为符号的左子树。//直至最后，只有一个数字符，此数字为之前符号的右子树，char preOpe='#';struct Node * PreNode='\0';struct Node * RootNode='\0';int i=0;int strLen=getStrLen(expression);while(i<strLen){if(i==0)//
        {int cNumber=expression[i]-48;i++;char cOperator=expression[i];i++;struct Node * LeftC=CreateNodesetV(cNumber,' ',1);struct Node * Root=CreateNodesetV(0,cOperator,2);insertNode(LeftC,Root,'L');preOpe=cOperator;PreNode=Root;RootNode=Root;}else{if(i+2<strLen)//get a number and operator
            {int cNumber=expression[i]-48;i++;char cOperator=expression[i];i++;if(lHeight(preOpe,cOperator)==1){struct Node * numberNode=CreateNodesetV(cNumber,' ',1);struct Node * OpeNode=CreateNodesetV(0,cOperator,2);insertNode(OpeNode,PreNode,'R');insertNode(numberNode,OpeNode,'L');preOpe=cOperator;PreNode=OpeNode;}else if (lHeight(preOpe,cOperator)==0){struct Node * numberNode=CreateNodesetV(cNumber,' ',1);struct Node * OpeNode=CreateNodesetV(0,cOperator,2);insertNode(RootNode,OpeNode,'L');insertNode(numberNode,PreNode,'R');preOpe=cOperator;PreNode=OpeNode;RootNode=OpeNode;}}else//last char
            {int cNumber=expression[i]-48;i++;struct Node * numberNode=CreateNodesetV(cNumber,' ',1);insertNode(numberNode,PreNode,'R');}}}if(RootNode!='\0'){visitTree(RootNode);printf("\nresult:%d",visitTree_2(RootNode));}return 0;
}int getStrLen(char * c)
{int i=0;while(c[i]!='\0'){i++;}return i;
}int lHeight(char oldc,char newl)
{if(oldc=='+'||oldc=='-'){if(newl=='*'||newl=='/'){return 1;}}else if(oldc=='#'){return 1;}return 0;
}

void CreateTree(char * expression,struct Node * PreNode,char preOpe);
struct Node * Root='\0';
int main()
{char * expression="2+3*5-4/2";char preOpe='#';struct Node * PreNode='\0';int strLen=getStrLen(expression);CreateTree(expression,PreNode,preOpe);if(Root!='\0'){visitTree(Root);printf("\nresult:%d",visitTree_2(Root));}return 0;
}void CreateTree(char * expression,struct Node * PreNode,char preOpe)
{int strLen=getStrLen(expression);if(strLen>1){int cNumber=expression[0]-48;char cOperator=expression[1];if(lHeight(preOpe,cOperator)==1){struct Node * numberNode=CreateNodesetV(cNumber,' ',1);struct Node * OpeNode=CreateNodesetV(0,cOperator,2);if(preOpe!='#'){insertNode(OpeNode,PreNode,'R');insertNode(numberNode,OpeNode,'L');preOpe=cOperator;PreNode=OpeNode;}else{insertNode(numberNode,OpeNode,'L');preOpe=cOperator;PreNode=OpeNode;Root=OpeNode;}}else if (lHeight(preOpe,cOperator)==0){struct Node * numberNode=CreateNodesetV(cNumber,' ',1);struct Node * OpeNode=CreateNodesetV(0,cOperator,2);insertNode(Root,OpeNode,'L');insertNode(numberNode,PreNode,'R');preOpe=cOperator;PreNode=OpeNode;Root=OpeNode;}CreateTree(expression+2,PreNode,preOpe);}else{int cNumber=expression[0]-48;struct Node * numberNode=CreateNodesetV(cNumber,' ',1);insertNode(numberNode,PreNode,'R');}
}