leetcode1300

class Solution:
    def findBestValue(self, arr: 'List[int]', target: int) -> int:
        l, r = 0, 10**5
        diff = abs(sum(arr) - target)
        res = collections.defaultdict(list)
        while l < r:
            m = (l + r) // 2
            s = sum([m if n > m else n for n in arr])
            if abs(s - target) <= diff:
                diff = abs(s - target)
                res[diff] += [m]
            if s < target:
                l = m + 1
            else: 
                r = m
        return min(res[diff])

参考：https://leetcode.com/problems/sum-of-mutated-array-closest-to-target/discuss/464211/Python-Binary-Search

补充另一个，使用Java实现的代码，可读性好一些：

class Solution {
    public int findBestValue(int[] arr, int target) {
        int left = 1;
        int right = target;
        
        int diff = 0;
        while (left < right) {
            int mid = left + (right - left) / 2;
            int sum = calSum(arr, mid);
            diff = sum - target;
            if (diff == 0) {
                return mid;
            } else if (diff < 0) {
                left = mid + 1;
            } else if (diff > 0) {
                right = mid;
            }
        }
        
        diff = calSum(arr, left) - target;
        int prevDiff = calSum(arr, left - 1) - target;
        
        // System.out.println("now left " + left + " diff " + diff);
        // System.out.println("Math.abs(prevDiff)" + Math.abs(prevDiff) + 
        //                    " Math.abs(diff)" + Math.abs(diff));
        
        return Math.abs(prevDiff) <= Math.abs(diff) ? left - 1 : left;
    }
    
    int calSum(int[] arr, int val) {
        int sum = 0;
        for (int i = 0; i < arr.length; i++) {
            if (arr[i] > val) {
                sum += val;
            } else {
                sum += arr[i];
            }
        }
        
        return sum;
    }
}

参考：https://leetcode.com/problems/sum-of-mutated-array-closest-to-target/discuss/464132/Java-3ms-binary-search-clean-readable-code

算法思路：二分查找。