_1176.java

package com.fishercoder.solutions;

/**
 * 1176. Diet Plan Performance
 *
 * A dieter consumes calories[i] calories on the i-th day.
 * Given an integer k, for every consecutive sequence of k days (calories[i], calories[i+1], ..., calories[i+k-1]
 * for all 0 <= i <= n-k), they look at T, the total calories consumed during that sequence of k days (calories[i] + calories[i+1] + ... + calories[i+k-1]):
 * If T < lower, they performed poorly on their diet and lose 1 point;
 * If T > upper, they performed well on their diet and gain 1 point;
 * Otherwise, they performed normally and there is no change in points.
 * Initially, the dieter has zero points. Return the total number of points the dieter has after dieting for calories.length days.
 *
 * Note that the total points can be negative.
 *
 * Example 1:
 * Input: calories = [1,2,3,4,5], k = 1, lower = 3, upper = 3
 * Output: 0
 * Explanation: Since k = 1, we consider each element of the array separately and compare it to lower and upper.
 * calories[0] and calories[1] are less than lower so 2 points are lost.
 * calories[3] and calories[4] are greater than upper so 2 points are gained.
 *
 * Example 2:
 * Input: calories = [3,2], k = 2, lower = 0, upper = 1
 * Output: 1
 * Explanation: Since k = 2, we consider subarrays of length 2.
 * calories[0] + calories[1] > upper so 1 point is gained.
 *
 * Example 3:
 * Input: calories = [6,5,0,0], k = 2, lower = 1, upper = 5
 * Output: 0
 * Explanation:
 * calories[0] + calories[1] > upper so 1 point is gained.
 * lower <= calories[1] + calories[2] <= upper so no change in points.
 * calories[2] + calories[3] < lower so 1 point is lost.
 *
 * Constraints:
 * 1 <= k <= calories.length <= 10^5
 * 0 <= calories[i] <= 20000
 * 0 <= lower <= upper
 * */
public class _1176 {
    public static class Solution1 {
        public int dietPlanPerformance(int[] calories, int k, int lower, int upper) {
            int sum = 0;
            int points = 0;
            for (int i = 0, j = 0; i <= calories.length - k && j < calories.length; j++) {
                sum += calories[j];
                if (j - i > k - 1) {
                    sum -= calories[i++];
                }
                if (j - i == k - 1) {
                    if (sum > upper) {
                        points++;
                    } else if (sum < lower) {
                        points--;
                    }
                }
            }
            return points;
        }
    }
}