5135. Sum Of Mutated Array Closest To Target V1.0

Author: ChlZhYa

LeetCode/5135. Sum Of Mutated Array Closest To Target/src/Solution.java

@@ -0,0 +1,45 @@
+import java.util.Arrays;
+
+/**
+ * @author changleamazing
+ * @date 2019/12/29 00:49
+ * source: https://leetcode-cn.com/problems/sum-of-mutated-array-closest-to-target/submissions/
+ **/
+public class Solution {
+
+    public int findBestValue(int[] arr, int target) {
+        int[] newArr = new int[arr.length + 1];
+        System.arraycopy(arr, 0, newArr, 1, arr.length);
+        Arrays.sort(newArr);
+        int length = newArr.length;
+
+        // 如果总和比 target 还小，则不需要替换。
+        if (Arrays.stream(newArr).sum() <= target) {
+            return newArr[length - 1];
+        }
+        // 已经遍历过的数字的和
+        int sum = 0;
+        // 剩下的数字个数
+        int leftNum;
+        // 剩下的数字和达到 target 需要的平均数
+        double leftAverage;
+        for (int i = 0; i < length - 1; i++) {
+            sum += newArr[i];
+            leftNum = length - i - 1;
+            leftAverage = (target - sum) / (double) leftNum;
+            // 如果平均数比下一个数小，则说明后面的数都要被替换
+            if (leftAverage <= newArr[i + 1]) {
+                // 如果 leftAverage <= x.5 ，则取 Math.floor(leftAverage);否则相反
+                return (int) (leftAverage - Math.floor(leftAverage) <= 0.5 ? Math.floor(leftAverage)
+                        : Math.ceil(leftAverage));
+            }
+        }
+        return target - sum;
+    }
+
+    public static void main(String[] args) {
+        int[] arr = {20693, 79539, 84645, 66727, 81334, 185, 14263, 53984, 71844, 71546};
+        new Solution().findBestValue(arr, 39947);
+
+    }
+}