53. Maximum Subarray

1.描述

Find the contiguous subarray within an array (containing at least one number) which has the largest sum.

For example, given the array [-2,1,-3,4,-1,2,1,-5,4],
the contiguous subarray [4,-1,2,1] has the largest sum = 6.

2.分析

简单的动态规划问题。

3.代码

int maxSubArray(int* nums, int numsSize) {
    if (NULL == nums) exit(0);
    if (1 == numsSize) return nums[0];
    int *dp = (int*)malloc(sizeof(int) * numsSize);
    if (NULL == dp) exit(0);
    
    int maxSum = dp[0]=nums[0];
    for (unsigned int i = 1; i < numsSize; ++i) {
        dp[i] = dp[i-1] > 0 ? dp[i-1] + nums[i] : nums[i];
        if (dp[i] > maxSum) maxSum = dp[i];
    }
    
    if (dp) {
        free(dp);
        dp = NULL;
    }
    return maxSum;
}