提交记录 #404

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

// 函数声明
char* replaceSubstring(char* source, const char* toReplace, const char* replacement);

int main() {
    char s[101]; // 源串 s，长度<=100
    char t[11];  // 被替换串 t，长度<=10
    char str[11]; // 替换串 str，长度<=10

    // 读取源串 s
    fgets(s, sizeof(s), stdin);
    s[strcspn(s, "\n")] = '\0'; // 去除换行符

    // 读取被替换串 t
    fgets(t, sizeof(t), stdin);
    t[strcspn(t, "\n")] = '\0'; // 去除换行符

    // 读取替换串 str
    fgets(str, sizeof(str), stdin);
    str[strcspn(str, "\n")] = '\0'; // 去除换行符

    // 执行替换
    char* result = replaceSubstring(s, t, str);
    if (result) {
        printf("%s\n", result); // 输出替换后的字符串
        free(result); // 释放动态分配的内存
    } else {
        printf("替换过程中发生错误。\n");
    }

    return 0;
}

// 字符串替换函数
char* replaceSubstring(char* source, const char* toReplace, const char* replacement) {
    char *pos, *dst;
    size_t toReplaceLen = strlen(toReplace);
    size_t replacementLen = strlen(replacement);
    size_t sourceLen = strlen(source);
    size_t neededLen = sourceLen + (replacementLen - toReplaceLen) * (sourceLen / toReplaceLen); // 估算需要的内存大小

    dst = (char*)malloc(neededLen + 1); // 分配内存
    if (!dst) return NULL;

    while ((pos = strstr(source, toReplace)) != NULL) {
        size_t offset = pos - source;
        memcpy(dst, source, offset); // 复制到替换点
        memcpy(dst + offset, replacement, replacementLen); // 复制替换字符串
        dst += offset + replacementLen; // 更新目标指针
        source += offset + toReplaceLen; // 更新源指针
    }
    strcpy(dst, source); // 复制剩余的字符串

    return dst;
}