[牛客网算法笔记]分糖果问题

【左神】

【问题描述】

【基础】

1.每个孩子不管得分多少，最少分到一个糖果。

2.任意两个相邻的孩子之间，得分较多的孩子必须拿多一些的糖果

根据左讲解的坡度我们来理解一下。见下图

大概思想应该是这样。代码我拷贝的别人的，图是我自己理解的。可以复制代码看一看。

public class Problem_07_CandyProblem {public static int candy1(int[] arr) {if (arr == null || arr.length == 0) {return 0;}int index = nextMinIndex1(arr, 0);int res = rightCands(arr, 0, index++);int lbase = 1;int next = 0;int rcands = 0;int rbase = 0;while (index != arr.length) {if (arr[index] > arr[index - 1]) {res += ++lbase;index++;} else if (arr[index] < arr[index - 1]) {next = nextMinIndex1(arr, index - 1);rcands = rightCands(arr, index - 1, next++);rbase = next - index + 1;res += rcands + (rbase > lbase ? -lbase : -rbase);lbase = 1;index = next;} else {res += 1;lbase = 1;index++;}}return res;}public static int nextMinIndex1(int[] arr, int start) {for (int i = start; i != arr.length - 1; i++) {if (arr[i] <= arr[i + 1]) {return i;}}return arr.length - 1;}public static int rightCands(int[] arr, int left, int right) {int n = right - left + 1;return n + n * (n - 1) / 2;}public static int candy2(int[] arr) {if (arr == null || arr.length == 0) {return 0;}int index = nextMinIndex2(arr, 0);int[] data = rightCandsAndBase(arr, 0, index++);int res = data[0];int lbase = 1;int same = 1;int next = 0;while (index != arr.length) {if (arr[index] > arr[index - 1]) {res += ++lbase;same = 1;index++;} else if (arr[index] < arr[index - 1]) {next = nextMinIndex2(arr, index - 1);data = rightCandsAndBase(arr, index - 1, next++);if (data[1] <= lbase) {res += data[0] - data[1];} else {res += -lbase * same + data[0] - data[1] + data[1] * same;}index = next;lbase = 1;same = 1;} else {res += lbase;same++;index++;}}return res;}public static int nextMinIndex2(int[] arr, int start) {for (int i = start; i != arr.length - 1; i++) {if (arr[i] < arr[i + 1]) {return i;}}return arr.length - 1;}public static int[] rightCandsAndBase(int[] arr, int left, int right) {int base = 1;int cands = 1;for (int i = right - 1; i >= left; i--) {if (arr[i] == arr[i + 1]) {cands += base;} else {cands += ++base;}}return new int[] { cands, base };}public static void main(String[] args) {int[] test1 = { 3, 0, 5, 5, 4, 4, 0 };System.out.println(candy1(test1));int[] test2 = { 3, 0, 5, 5, 4, 4, 0 };System.out.println(candy2(test2));}}