#include "stdio.h"
#include "string.h"
#include "stdlib.h"
#include "stack"
using namespace std;
const char str[] = "3*4+5-2/1";
struct tree
{
char c;
struct tree* left;
struct tree* right;
};
stack<struct tree*> subTreeStack;
stack<char> operatorStack;
struct tree* BuildTree()
{
struct tree* node;
for (unsigned int pos = 0; pos < strlen(str); pos++)
{
if (str[pos] - '0' >= 0 && str[pos] - '0' <= 9) //若是数字则作为叶子节点
{
node = (struct tree*) malloc(sizeof(struct tree));
node->c = str[pos];
node->left = NULL;
node->right = NULL;
subTreeStack.push(node);
}
else if (str[pos] == '*' || str[pos] == '/' || str[pos] == '+' || str[pos] == '-')
{
if (!operatorStack.empty() && (str[pos] == '+' || str[pos] == '-')) //若优先级比栈顶元素低
{
node = (struct tree*) malloc(sizeof(struct tree));
node->c = operatorStack.top();
node->right = subTreeStack.top();
subTreeStack.pop();
node->left = subTreeStack.top();
subTreeStack.pop();
subTreeStack.push(node);
operatorStack.pop();
operatorStack.push(str[pos]);
}
else
operatorStack.push(str[pos]);
}
}
while(!operatorStack.empty())
{
node = (struct tree*) malloc(sizeof(struct tree));
node->c = operatorStack.top();
operatorStack.pop();
node->right = subTreeStack.top();
subTreeStack.pop();
node->left = subTreeStack.top();
subTreeStack.pop();
subTreeStack.push(node);
}
return subTreeStack.top();
}
void PrintTree(struct tree* node)
{
if (node == NULL)
return;
PrintTree(node->left);
printf("%c", node->c);
PrintTree(node->right);
}
void main()
{
struct tree* root = BuildTree();
PrintTree(root);
}
【数据结构】中缀表达式构造二叉树转换成后缀表达式
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转载自blog.csdn.net/IGGIRing/article/details/72869601
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