剑指offer第三十一题:连续子数组的最大和
1 //============================================================================ 2 // Name : JZ-C-31.cpp 3 // Author : Laughing_Lz 4 // Version : 5 // Copyright : All Right Reserved 6 // Description : 连续子数组的最大和 7 //============================================================================ 8 9 #include <iostream> 10 #include <stdio.h> 11 using namespace std; 12 13 bool g_InvalidInput = false; 14 15 int FindGreatestSumOfSubArray(int *pData, int nLength) { 16 if ((pData == NULL) || (nLength <= 0)) { 17 g_InvalidInput = true; 18 return 0; 19 } 20 21 g_InvalidInput = false; 22 23 int nCurSum = 0; 24 int nGreatestSum = 0x80000000;//最小的整数。int 4个字节,最小数:-2^31:0x80000000,最大数:2^32-1:0x7fffffff。(均为补码) 25 for (int i = 0; i < nLength; ++i) { 26 if (nCurSum <= 0) 27 nCurSum = pData[i]; 28 else 29 nCurSum += pData[i]; 30 31 if (nCurSum > nGreatestSum) 32 nGreatestSum = nCurSum; 33 } 34 35 return nGreatestSum; 36 } 37 38 // ====================测试代码==================== 39 void Test(char* testName, int* pData, int nLength, int expected, 40 bool expectedFlag) { 41 if (testName != NULL) 42 printf("%s begins: ", testName); 43 44 int result = FindGreatestSumOfSubArray(pData, nLength); 45 if (result == expected && expectedFlag == g_InvalidInput) 46 printf("Passed. "); 47 else 48 printf("Failed. "); 49 } 50 51 // 1, -2, 3, 10, -4, 7, 2, -5 52 void Test1() { 53 int data[] = { 1, -2, 3, 10, -4, 7, 2, -5 }; 54 Test("Test1", data, sizeof(data) / sizeof(int), 18, false); 55 } 56 57 // 所有数字都是负数 58 // -2, -8, -1, -5, -9 59 void Test2() { 60 int data[] = { -2, -8, -1, -5, -9 }; 61 Test("Test2", data, sizeof(data) / sizeof(int), -1, false); 62 } 63 64 // 所有数字都是正数 65 // 2, 8, 1, 5, 9 66 void Test3() { 67 int data[] = { 2, 8, 1, 5, 9 }; 68 Test("Test3", data, sizeof(data) / sizeof(int), 25, false); 69 } 70 71 // 无效输入 72 void Test4() { 73 Test("Test4", NULL, 0, 0, true); 74 } 75 76 int main(int argc, char** argv) { 77 Test1(); 78 Test2(); 79 Test3(); 80 Test4(); 81 82 return 0; 83 }