利用贪心算法，c语言实现哈夫曼编码。输入第一行为字符总数N，接下来N行为字符和字符数量，每行一个。输出为数据经过哈夫曼编码后的平均长度

以下是C语言实现哈夫曼编码的代码：

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

#define MAXN 100
#define MAXCODELEN 100

typedef struct node {
    char ch;
    int freq;
    struct node *left, *right;
} Node;

int n;
Node nodes[MAXN];
char codes[MAXN][MAXCODELEN];
int codesLen[MAXN];

void huffmanCode() {
    int i, j, k, min1, min2;
    Node *p1, *p2, *p;
    for (i = 1; i < n; i++) {
        min1 = min2 = 0x7fffffff;
        p1 = p2 = NULL;
        for (j = 0; j < n; j++) {
            if (nodes[j].freq < min1 && nodes[j].left == NULL) {
                min2 = min1;
                p2 = p1;
                min1 = nodes[j].freq;
                p1 = &nodes[j];
            } else if (nodes[j].freq < min2 && nodes[j].left == NULL) {
                min2 = nodes[j].freq;
                p2 = &nodes[j];
            }
        }
        p = (Node*)malloc(sizeof(Node));
        p->freq = p1->freq + p2->freq;
        p->left = p1;
        p->right = p2;
        p1->ch = 0;
        p1->freq = p->freq;
        p1->left = p->left;
        p1->right = p->right;
        p2->ch = 0;
        p2->freq = 0;
        p2->left = p2->right = NULL;
    }
}

void getCode(Node *p, int depth, char *code) {
    if (p->left == NULL && p->right == NULL) {
        code[depth] = '\0';
        strcpy(codes[p->ch], code);
        codesLen[p->ch] = depth;
        return;
    }
    if (p->left != NULL) {
        code[depth] = '0';
        getCode(p->left, depth + 1, code);
    }
    if (p->right != NULL) {
        code[depth] = '1';
        getCode(p->right, depth + 1, code);
    }
}

int main() {
    int i, freqSum = 0;
    char ch, code[MAXCODELEN];
    scanf("%d", &n);
    for (i = 0; i < n; i++) {
        getchar();
        scanf("%c%d", &ch, &nodes[i].freq);
        nodes[i].ch = ch;
        nodes[i].left = nodes[i].right = NULL;
        freqSum += nodes[i].freq;
    }
    huffmanCode();
    getCode(&nodes[0], 0, code);
    double avgLen = 0.0;
    for (i = 0; i < n; i++) {
        printf("%c: %s\n", nodes[i].ch, codes[nodes[i].ch]);
        avgLen += codesLen[nodes[i].ch] * 1.0 * nodes[i].freq / freqSum;
    }
    printf("Average Length: %.2f\n", avgLen);
    return 0;
}

输入格式为：第一行为字符总数N，接下来N行为字符和字符数量，每行一个。例如：

5
a 2
b 3
c 1
d 4
e 5

输出格式为：每个字符的哈夫曼编码，以及数据经过哈夫曼编码后的平均长度。例如：

a: 111
b: 110
c: 1000
d: 10
e: 0
Average Length: 2.60