求数组中连续最大的和

/**********************************
    求数组中连续字串的最大和
    并返回起始位置和终止位置
***********************************/
#include <stdio.h>
#define elemType int

elemType max(elemType a,elemType b) {
    if(a>b) return a;
    return b;
}

elemType maxSumOfContinueSubStr(elemType *a,int length) {
    if(a == NULL || length <= 0)
        return 0;
    int maxSum=0,sumOfEnd=0;
    int leftIndex=0,rightIndex=-1;
    for(int i=0;i<length;i++) {
        sumOfEnd = max(0,sumOfEnd+a[i]);
        if(sumOfEnd == 0) leftIndex = i+1+1; //下一个位置开始

        maxSum = max(maxSum,sumOfEnd);
        if(maxSum == sumOfEnd) rightIndex = i+1;   //当前位置
    }

    printf("from: %d to %d",leftIndex,rightIndex);
    return maxSum;
}

void main() {
    elemType a[11] = {-3,2,-1,2,-4,5,6,4,-9,1,2};
    elemType sum = maxSumOfContinueSubStr(a,10);
    printf("max sum of continue sub str is:%d\n",sum);
}