求子数组的最大和

输入一个整形数组,数组里有正数也有负数。
数组中连续的一个或多个整数组成一个子数组,每个子数组都有一个和。
求所有子数组的和的最大值。要求时间复杂度为O(n)。

例如输入的数组为1, -2, 3, 10, -4, 7, 2, -5,和最大的子数组为3, 10, -4, 7, 2,
因此输出为该子数组的和18。

#include<stdio.h>
int subStrSum(int* s, int len)
{
    int i = 1, curSum = s[0], maxSum = s[0];
    while(i < len)
    {
        if(curSum > 0 &&curSum + s[i] > 0)//当前和为负数或者加当前元素后为负数,则不进行累加,而赋当前和为当前元素
            curSum += s[i];
        else
            curSum = s[i];
        i += 1;
        if(curSum > maxSum)
            maxSum = curSum;
    }
    return maxSum;
}
void main(){
    int s[] = {-2,-2,-5,-2,-1,-6,-11,-7,-3};
    int maxSum = subStrSum(s,9);
    printf("%d
",maxSum);
}

 改进,输出该子数组

#include<stdio.h>
typedef struct subStr{
    int start;
    int length;
    int sum;
}str;
str subStrSum(int* s, int len)
{
    str s1;
    int i = 1, curSum = s[0];
    s1.start = 0;
    s1.length =1;
    s1.sum = s[0];
    int length = 1, start = 0;
    while(i < len)
    {
        if(curSum > 0 &&curSum + s[i] > 0)
        {
            curSum += s[i];
            length += 1;
        }
        else
        {
            curSum = s[i];
            start = i;
            length = 1;
        }      
        if(curSum > s1.sum)
        {
            s1.start = start;
            s1.length = length;
            s1.sum = curSum;
        }
        i += 1;
    }
    return s1;
}
void main(){
    int s[] = {1,2,-5,2,1,6,-11,7,-3};
    str str1 = subStrSum(s,9);
    int i ;
    for(i = 0; i < str1.length; i++)
        printf("%d,",s[str1.start+i]);
    printf("sum is %d
",str1.sum);
}
原文地址:https://www.cnblogs.com/idealing/p/4009230.html