C++ 解法, 执行用时: 3ms, 内存消耗: 556KB, 提交时间: 2021-11-14

class Solution {
public:
    /**
     * 最大乘积
     * @param A int整型一维数组 
     * @param ALen int A数组长度
     * @return long长整型
     */
    long long solve(int* A, int ALen) {
        // write code here
        if(ALen < 3) return 0;
        long long min_num[2] = {INT_MAX, INT_MAX};
        long long max_num[3] = {INT_MIN, INT_MIN, INT_MIN};
        for(int i=0; i<ALen; ++i){
            if(A[i] < min_num[1]){
                if(A[i] < min_num[0]){
                    min_num[1] = min_num[0];
                    min_num[0] = A[i];
                }
                else min_num[1] = A[i];
            }
            if(A[i] > max_num[2]){
                if(A[i] > max_num[0]) {
                    max_num[2] = max_num[1];
                    max_num[1] = max_num[0];
                    max_num[0] = A[i];
                }
                else if(A[i] > max_num[1]){
                    max_num[2] = max_num[1];
                    max_num[1] = A[i];
                }
                else max_num[2] = A[i];
            }
        }
        return max(min_num[0]*min_num[1]*max_num[0], max_num[0]*max_num[1]*max_num[2]);
    }
};

C++ 解法, 执行用时: 3ms, 内存消耗: 576KB, 提交时间: 2021-07-25

class Solution {
public:
    /**
     * 最大乘积
     * @param A int整型一维数组 
     * @param ALen int A数组长度
     * @return long长整型
     */
    long long solve(int* A, int ALen) {
        long long max = LLONG_MIN, max2 = LLONG_MIN, max3 = LLONG_MIN;
        long long min = LLONG_MAX, min2 = LLONG_MAX;

        for (int i = 0; i < ALen; i++) {
		if (A[i] > max) {
			max3 = max2;
			max2 = max;
			max = A[i];
		}
		else if (A[i] > max2) {
			max3 = max2;
			max2 = A[i];
		}
		else if (A[i] > max3)
			max3 = A[i];
		if (A[i] < min) {
			min2 = min;
			min = A[i];
		}
		else if (A[i] < min2)
			min2 = A[i];
	}

        long long MAX = max*max2*max3;
        long long MAX2 = max*min*min2;
        if (MAX > MAX2)
            return MAX;
        else
            return MAX2;
        // write code here
    }
};

C++ 解法, 执行用时: 3ms, 内存消耗: 632KB, 提交时间: 2021-11-28

class Solution {
public:
    /**
     * 最大乘积
     * @param A int整型一维数组 
     * @param ALen int A数组长度
     * @return long长整型
     */
    long long solve(int* A, int ALen) {
        // write code here
        long long max1 =INT_MIN, max2 = INT_MIN, max3 = INT_MIN;
        long long min1 = INT_MAX,min2 = INT_MAX;
        
        for(int i = 0;i<ALen;++i)
        {
            if(A[i]>max1)
            {
                max3 = max2;
                max2 = max1;
                max1 = A[i];
            }
            else if(A[i]>max2)
            {
                max3 = max2;
                max2 = A[i];
            }
            else if(A[i] > max3)
            {
                max3 = A[i];
            }
            
            if(A[i]<min1)
            {
                min2 = min1;
                min1 = A[i];
            }
            else if(A[i]<min2)
            {
                min2 = A[i];
            }
        }
        
        long long ret = max(max1*max2*max3,min1*min2*max1);
        return ret;
        
    }
};

C++ 解法, 执行用时: 3ms, 内存消耗: 632KB, 提交时间: 2021-07-25

class Solution {
public:
    /**
     * 最大乘积
     * @param A int整型一维数组 
     * @param ALen int A数组长度
     * @return long长整型
     */
    long long solve(int* A, int ALen) {
        if (ALen == 3)
		return A[0] * A[1] * A[2];
	// write code here
	long long max1 = LLONG_MIN;
	long long max2 = max1, max3 = max1;
	long long min1 = LLONG_MAX;
	long long min2 = min1;
	for (int i = 0; i<ALen; i++) {
		long long item = A[i];
		if (item>max1) {
			max3 = max2;
			max2 = max1;
			max1 = item;
		}
		else if (item>max2) {
			max3 = max2;
			max2 = item;
		}
		else if (item>max3)
			max3 = item;
		if (item<min1) {
			min2 = min1;
			min1 = item;
		}
		else if (item<min2)
			min2 = item;
	}
	cout << max3 << endl;
	cout << max2 << endl;
	cout << max1 << endl;
	cout << min1 << endl;
	cout << min2 << endl;
	long long result1 = max1*max2*max3;
	long long result2 = min1*min2*max1;
	cout << result1<< endl;
	cout << result2 << endl;
	return result1>result2?result1:result2;
        
    }
};

C++ 解法, 执行用时: 3ms, 内存消耗: 640KB, 提交时间: 2021-11-01

class Solution {
public:
    /**
     * 最大乘积
     * @param A int整型一维数组 
     * @param ALen int A数组长度
     * @return long长整型
     */
long long solve(int* A, int ALen)
{
    sort(A,A+ALen);
    long long ans=1;
        ans=(long long)A[0]*A[1];
        ans=ans*A[ALen-1];
    long long ans1;
        ans1=(long long )A[ALen-1]*A[ALen-2];
        ans1=ans1*A[ALen-3];
    return max(ans,ans1);
}

};