Given an integer array nums, find the contiguous subarray (containing at least one number) which has the largest sum and return its sum.
1. first we need to define sum as the maximum at present. then define res as the maximum in the contiguous subarray.
2.then divide the question into two condition.
when sum>0 that means we should add the next number of the array. so long as we have the possibility to get the larger sum.
so we write sum+=array[i];
when sum<0 that means we just need to give the next number's value to the sum. in order not to get the sum smaller. so we can't add this number.
3.now we talk about res. the largest contiguous subarray's sum. we use this varible to mark the largest sum. So we can write
res=Math.max(res,sum)
public int maxSubArray(int[] nums) {
int res=nums[0];
int sum=0;
for(int num:nums){
if(sum>0){
sum+=num;
}
else{
sum=num;
}
res=Math.max(res,sum);
}
return res;
}