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最新推荐文章于 2022-11-22 22:17:01 发布

转载最新推荐文章于 2022-11-22 22:17:01 发布 · 151 阅读

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原文链接：http://www.cnblogs.com/asenyang/p/10506477.html

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#数据结构与算法

 1 func largestSumAfterKNegations(A []int, K int) int {
 2     sort.Ints(A)
 3     var negatives int
 4     var zeros int
 5     var positives int
 6     var negativeAry []int
 7     var positiveAry []int
 8     for n := range A {
 9         if A[n] < 0 {
10             negatives++
11             negativeAry = append(negativeAry, A[n])
12         } else if A[n] == 0 {
13             zeros++
14         } else {
15             positives++
16             positiveAry = append(positiveAry, A[n])
17         }
18     }
19     var sum int
20     if K <= negatives { //只需要把负数变正数，把最小的（绝对值大的）K个负数变正数
21         for i := 0; i < K; i++ {
22             sum += negativeAry[i] * -1
23         }
24         for i := K; i < negatives; i++ {
25             sum += negativeAry[i]
26         }
27         for i := 0; i < positives; i++ {
28             sum += positiveAry[i]
29         }
30     } else { //将全部的负数都变成正数，还不够
31         if zeros > 0 || (K-negatives)%2 == 0 {
32             //剩下的变化次数，全变0，或者反复的变偶数次同一个正数（也可以是一个已经变成正数的负数）
33             for i := 0; i < negatives; i++ {
34                 sum += negativeAry[i] * -1
35             }
36             for i := 0; i < positives; i++ {
37                 sum += positiveAry[i]
38             }
39         } else {
40             //先把负数的绝对值累加
41             for i := 0; i < negatives; i++ {
42                 sum += negativeAry[i] * -1
43             } //再把正数的绝对值累加
44             for i := 0; i < positives; i++ {
45                 sum += positiveAry[i]
46             } //判断全部已经都变成正数的数组中，绝对值最小的数字
47             //将绝对值最小的这个数字，减2次
48             if (negatives == 0 && positives > 0) || (positives > 0 && negatives > 0 && positiveAry[0] <= negativeAry[negatives-1]*-1) {
49                 sum += positiveAry[0] * -2
50                 return sum
51             }
52             if (positives == 0 && negatives > 0) || (positives > 0 && negatives > 0 && positiveAry[0] > negativeAry[negatives-1]*-1) {
53                 sum += negativeAry[negatives-1] * 2
54                 return sum
55             }
56         }
57 
58     }
59     return sum
60 }

上面这个一定觉得很啰嗦，那就来个简单的：

 1 func largestSumAfterKNegations(A []int, K int) int {
 2     sort.Ints(A)
 3     i := 0
 4     for i < len(A) && K > 0 && A[i] < 0 {
 5         A[i] = -A[i]
 6         i++
 7         K--
 8     }
 9     sum := 0
10     sort.Ints(A)
11     for j := range A {
12         sum += A[j]
13     }
14     if K > 0 && K%2 == 1 {
15         min := A[0]
16         sum -= min * 2
17     }
18     return sum
19 }