陈利人微博题的实现代码：http://weibo.com/1915548291/AcqqPxnEp #面试题#N个孩子站成一排，每个人分给一个权重。按照如下的规则分配糖果： 每个孩子至少有一个糖果；所分配权重较高的孩子，会比他的邻居获得更多的糖果。 问题是，最少需要多少个糖果？关注微信公众账号“待字闺中”，了解更多。 http://oj.leetcode.com/problems/candy/。 PS： 现在代码移到了 https://github.com/oldratlee/leetcode/blob/master/src/main/java/candy/Solution.java

Candy.java

/** 通过的UT Case：
    assertEquals(0, Candy.calcCandyCount(new int[]{}));

    assertEquals(1, Candy.calcCandyCount(new int[]{1,}));
    assertEquals(1, Candy.calcCandyCount(new int[]{100,}));

    assertEquals(2, Candy.calcCandyCount(new int[]{1, 1,}));
    assertEquals(3, Candy.calcCandyCount(new int[]{1, 2,}));
    assertEquals(3, Candy.calcCandyCount(new int[]{2, 1,}));

    assertEquals(3, Candy.calcCandyCount(new int[]{1, 1, 1}));
    assertEquals(4, Candy.calcCandyCount(new int[]{1, 1, 2}));
    assertEquals(4, Candy.calcCandyCount(new int[]{2, 1, 1}));
    assertEquals(4, Candy.calcCandyCount(new int[]{2, 2, 1}));
    assertEquals(5, Candy.calcCandyCount(new int[]{2, 1, 2}));

    assertEquals(6, Candy.calcCandyCount(new int[]{1, 2, 3}));
    assertEquals(6, Candy.calcCandyCount(new int[]{3, 2, 1}));
    assertEquals(4, Candy.calcCandyCount(new int[]{1, 2, 1}));

    assertEquals(7, Candy.calcCandyCount(new int[]{1, 2, 3, 3}));

    assertEquals(9, Candy.calcCandyCount(new int[]{1, 2, 3, 3, 1}));
    assertEquals(10, Candy.calcCandyCount(new int[]{1, 2, 3, 3, 3, 1}));
*/

import java.util.ArrayList;
import java.util.List;

/**
 * @author ding.lid
 */
public class Candy {
    private static class UndulationInfo {
        public UndulationInfo(int adjust, int upLen, int downLen) {
            this.adjust = adjust;
            this.upLen = upLen;
            this.downLen = downLen;
        }

        public int adjust;
        public int upLen;
        public int downLen;
    }

    public static int calcCandyCount(int[] weights) {
        final int length = weights.length;

        int adjust = 0;
        List<UndulationInfo> infoList = new ArrayList<UndulationInfo>();
        for (int i = 0; i < length; ) {
            int up = 0;
            int down = 0;
            while (i + 1 < length && weights[i + 1] > weights[i]) {
                ++up;
                ++i;
            }
            while (i + 1 < length && weights[i + 1] < weights[i]) {
                ++down;
                ++i;
            }
            infoList.add(new UndulationInfo(adjust, up, down));

            if (i == length - 1) break;
            if (weights[i + 1] == weights[i]) {
                adjust = 0; // 如果相等，新起一个没有起点重合的山坡
                ++i;
            } else {
                adjust = -1; // 如果不相等（实际上是重新上坡），新起一个起点重合的山坡。校正值为-1
            }
        }

        return calcFromUndulationInfo(infoList);
    }

    private static int calcFromUndulationInfo(List<UndulationInfo> infoList) {
        int count = 0;
        for (UndulationInfo info : infoList) {
            count += info.adjust // 校正值
                    + info.upLen * (info.upLen + 1) / 2 // 上升坡的和
                    + info.downLen * (info.downLen + 1) / 2 // 下降坡的和
                    + Math.max(info.upLen, info.downLen) + 1; // 坡顶的值
        }
        return count;
    }
}