把数组排成最小的数－C++

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// 面试题45：把数组排成最小的数 // 题目：输入一个正整数数组，把数组里所有数字拼接起来排成一个数，打印能拼 // 接出的所有数字中最小的一个。例如输入数组{3, 32, 321}，则打印出这3个数 // 字能排成的最小数字321323。 #include "cstdio" #include <string> #include <algorithm> int compare(const void *strNumber1, const void *strNumber2); // int型整数用十进制表示最多只有10位 const int g_MaxNumberLength = 10; char *g_StrCombine1 = new char[g_MaxNumberLength * 2 + 1]; char *g_StrCombine2 = new char[g_MaxNumberLength * 2 + 1]; void PrintMinNumber(const int *numbers, int length) { if (numbers == nullptr || length <= 0) return; char **strNumbers = (char **)(new int[length]); for (int i = 0; i < length; ++i) { strNumbers[i] = new char[g_MaxNumberLength + 1]; sprintf(strNumbers[i], "%d", numbers[i]); } qsort(strNumbers, length, sizeof(char *), compare); for (int i = 0; i < length; ++i) printf("%s", strNumbers[i]); printf("\n"); for (int i = 0; i < length; ++i) delete[] strNumbers[i]; delete[] strNumbers; } // 如果[strNumber1][strNumber2] > [strNumber2][strNumber1], 返回值大于0 // 如果[strNumber1][strNumber2] = [strNumber2][strNumber1], 返回值等于0 // 如果[strNumber1][strNumber2] < [strNumber2][strNumber1], 返回值小于0 int compare(const void *strNumber1, const void *strNumber2) { // [strNumber1][strNumber2] strcpy(g_StrCombine1, *(const char **)strNumber1); strcat(g_StrCombine1, *(const char **)strNumber2); // [strNumber2][strNumber1] strcpy(g_StrCombine2, *(const char **)strNumber2); strcat(g_StrCombine2, *(const char **)strNumber1); return strcmp(g_StrCombine1, g_StrCombine2); } // ====================测试代码==================== void Test(const char *testName, int *numbers, int length, const char *expectedResult) { if (testName != nullptr) printf("%s begins:\n", testName); if (expectedResult != nullptr) printf("Expected result is: \t%s\n", expectedResult); printf("Actual result is: \t"); PrintMinNumber(numbers, length); printf("\n"); } void Test1() { int numbers[] = {3, 5, 1, 4, 2}; Test("Test1", numbers, sizeof(numbers) / sizeof(int), "12345"); } void Test2() { int numbers[] = {3, 32, 321}; Test("Test2", numbers, sizeof(numbers) / sizeof(int), "321323"); } void Test3() { int numbers[] = {3, 323, 32123}; Test("Test3", numbers, sizeof(numbers) / sizeof(int), "321233233"); } void Test4() { int numbers[] = {1, 11, 111}; Test("Test4", numbers, sizeof(numbers) / sizeof(int), "111111"); } // 数组中只有一个数字 void Test5() { int numbers[] = {321}; Test("Test5", numbers, sizeof(numbers) / sizeof(int), "321"); } void Test6() { Test("Test6", nullptr, 0, "Don't print anything."); } int main(int argc, char *argv[]) { Test1(); Test2(); Test3(); Test4(); Test5(); Test6(); return 0; } // ------ Output ------ /* Test1 begins: Expected result is: 12345 Actual result is: 1245�a`5 Test2 begins: Expected result is: 321323 Actual result is: 32132�a`5 Test3 begins: Expected result is: 321233233 Actual result is: 32123323�a`5 Test4 begins: Expected result is: 111111 Actual result is: 11111�a`5 Test5 begins: Expected result is: 321 Actual result is: 321 Test6 begins: Expected result is: Don't print anything. Actual result is: */