Create C8MaxSum.md

jasonpy99 · Jul 7, 2018 · 4cb403d · 4cb403d
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diff --git a/CodingInterviewGuide/C8MaxSum.md b/CodingInterviewGuide/C8MaxSum.md
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+```
+package Chapter8;
+
+/**
+ * @author Ethan
+ * @desc 子数组的最大累加和问题 
+ */
+public class C8MaxSum {
+
+	/**
+	 * @author Ethan
+	 * @desc 子数组的最大累加和
+	 * 如果全负，则负值中的最大值
+	 * 如果有正，当前和cur为负则更新为0
+	 */
+	public int maxSum(int[] arr){
+		//1-异常参数检测 
+		if(arr == null || arr.length == 0){
+			return 0;
+		}
+		//2-初始化 cur:当前和 max:最大值
+		int cur = 0;
+		int max = Integer.MIN_VALUE;
+		//3-遍历求和寻找最大值
+		for(int i = 0; i < arr.length; i++){
+			cur += arr[i];
+			max = Math.max(max,cur);
+			cur = cur < 0 ? 0 : cur;
+		}
+		return max;
+	}
+	
+	public static void main(String[] args) {
+		C8MaxSum c8 = new C8MaxSum();
+		//1-全为负
+		int[] arr1 = {-3,-2,-1,-5};
+		//2-有正有负
+		int[] arr2 = {1,-2,3,-5};
+		int res = c8.maxSum(arr2);
+		System.out.println(res);
+	}
+}
+
+```