finish 135

Author: BaffinLee

135. Candy.js

@@ -0,0 +1,35 @@
+/**
+ * 135. Candy
+ * 
+ * There are N children standing in a line. Each child is assigned a rating value.
+ * 
+ * You are giving candies to these children subjected to the following requirements:
+ * 
+ * Each child must have at least one candy.
+ * Children with a higher rating get more candies than their neighbors.
+ * What is the minimum candies you must give?
+ */
+
+/**
+ * @param {number[]} ratings
+ * @return {number}
+ */
+var candy = function(ratings) {
+	var len = ratings.length;
+	var res = [];
+	var sum = 0;
+	for (var i = 0; i < len; i++) {
+			res.push((i !== 0 && ratings[i] > ratings[i - 1]) ? (res[i - 1] + 1) : 1);
+	}
+	for (var j = len - 1; j >= 0; j--) {
+			if (j !== len - 1 && ratings[j] > ratings[j + 1]) res[j] = Math.max(res[j], res[j + 1] + 1);
+			sum += res[j];
+	}
+	return sum;
+};
+
+// 分两次循环
+// 第一次从左到右，上升的依次加 1，下降或者相等的填 1
+// 第二次从右到左，上升的依次加 1，下降或者相等的不管
+// (注意最高点可能之前填充过，需要取 max 值，才能同时满足两边的需求)
+// 第二次处理完后计算总和，省得另开一个循环