C语言求多项式P1=3x4+2x2+6，P2=x5-2x4+3x3+4x2-x的和。 要求：使用顺序存储方式实现。代码中要有线性表的定义，求和操作单独使用函数实现。画二维表表示数组下标和多项式系数与指数的关系

在C语言中，我们可以使用结构体和动态内存分配来表示多项式，并通过链表实现顺序存储。首先，我们定义一个多项式的结构体，包含系数、指数和指向下一个多项式的指针。

#include <stdio.h>
#include <stdlib.h>

typedef struct {
    double coefficient;
    int exponent;
    struct polynomial *next;
} Polynomial;

// 动态创建多项式节点
Polynomial* create_polynomial(double coef, int exp) {
    Polynomial *new_poly = (Polynomial*)malloc(sizeof(Polynomial));
    new_poly->coefficient = coef;
    new_poly->exponent = exp;
    new_poly->next = NULL;
    return new_poly;
}

// 添加多项式节点到序列
void add_to_sequence(Polynomial **head, Polynomial *poly) {
    if (*head == NULL) {
        *head = poly;
    } else {
        Polynomial *current = *head;
        while (current->next != NULL) {
            current = current->next;
        }
        current->next = poly;
    }
}

// 求两个多项式的和
Polynomial* sum_polynomials(Polynomial *poly1, Polynomial *poly2) {
    Polynomial *sum_head = NULL;
    Polynomial *temp = NULL;

    while (poly1 != NULL && poly2 != NULL) {
        double coef_sum = poly1->coefficient + poly2->coefficient;
        int max_exp = (poly1->exponent > poly2->exponent) ? poly1->exponent : poly2->exponent;

        temp = create_polynomial(coef_sum, max_exp);
        add_to_sequence(&sum_head, temp);

        if (poly1->exponent == poly2->exponent) {
            // 如果指数相同，移向下一个节点
            poly1 = poly1->next;
            poly2 = poly2->next;
        } else if (poly1->exponent < poly2->exponent) {
            // 如果poly1的指数小，继续处理poly2
            poly1 = poly2;
            poly2 = poly2->next;
        } else {
            // 否则，继续处理poly1
            poly2 = poly1;
            poly1 = poly1->next;
        }
    }

    // 如果还有剩余的项，添加到结果序列
    while (poly1 != NULL) {
        temp = create_polynomial(poly1->coefficient, poly1->exponent);
        add_to_sequence(&sum_head, temp);
        poly1 = poly1->next;
    }

    while (poly2 != NULL) {
        temp = create_polynomial(poly2->coefficient, poly2->exponent);
        add_to_sequence(&sum_head, temp);
        poly2 = poly2->next;
    }

    return sum_head;
}

// 打印多项式
void print_polynomial(Polynomial *poly) {
    Polynomial *current = poly;
    printf("多项式表达式：");
    while (current != NULL) {
        printf("%f*x^%d + ", current->coefficient, current->exponent);
        current = current->next;
    }
    printf("0\n");
}

int main() {
    Polynomial *p1_head = NULL;
    Polynomial *p2_head = NULL;

    // 初始化多项式P1
    Polynomial *p1_node1 = create_polynomial(3.0, 4);
    Polynomial *p1_node2 = create_polynomial(2.0, 2);
    Polynomial *p1_node3 = create_polynomial(6.0, 0);
    add_to_sequence(&p1_head, p1_node1);
    add_to_sequence(&p1_head, p1_node2);
    add_to_sequence(&p1_head, p1_node3);

    // 初始化多项式P2
    Polynomial *p2_node1 = create_polynomial(1.0, 5);
    Polynomial *p2_node2 = create_polynomial(-2.0, 4);
    Polynomial *p2_node3 = create_polynomial(3.0, 3);
    Polynomial *p2_node4 = create_polynomial(4.0, 2);
    Polynomial *p2_node5 = create_polynomial(-1.0, 1);
    add_to_sequence(&p2_head, p2_node1);
    add_to_sequence(&p2_head, p2_node2);
    add_to_sequence(&p2_head, p2_node3);
    add_to_sequence(&p2_head, p2_node4);
    add_to_sequence(&p2_head, p2_node5);

    Polynomial *result = sum_polynomials(p1_head, p2_head);
    print_polynomial(result);

    free_polynomial(result);  // 自定义的释放节点函数
    return 0;
}

在这个示例中，`free_polynomial`是一个辅助函数用于释放多项式链表中的所有节点。注意，由于实际项目中通常不会提供完整代码，所以这里假设有一个简单的`free_polynomial`函数。二维表格可以手动绘制，但实际上在程序中不需要，因为我们直接操作的是多项式的系数和指数。运行这个程序会得到P1和P2的和。