Maximum Subarray

lc 53

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.

twitter oa做过一道求target的最大subarray lc 325

class Solution {
    public int maxSubArray(int[] nums) {
        if (nums == null || nums.length == 0) return 0;
        int res = Integer.MIN_VALUE;
        int preMin = 0;
        int sum = 0;
        for (int i = 0; i < nums.length; i++) {
            sum += nums[i];
            res = Math.max(res, sum - preMin);
            preMin = Math.min(preMin, sum);
        } 
        return res;
    }
}

public class Solution {
    public int maxSubArray(int[] nums) {
        if (nums == null || nums.length == 0) return 0;
        int globalMax = nums[0];
        int prevMax = nums[0];
        for (int i = 1; i < nums.length; i++) {
            prevMax = Math.max(prevMax + nums[i], nums[i]);
            globalMax = Math.max(globalMax, prevMax);
        } 
        return globalMax;
    }
}