_1423.java

packagecom.fishercoder.solutions.secondthousand;

publicclass_1423 {
publicstaticclassSolution1 {
publicintmaxScore(int[] cardPoints, intk) {
intmaxScore = 0;
if (cardPoints.length <= k) {
for (intpoint : cardPoints) {
maxScore += point;
 }
returnmaxScore;
 }
for (inti = 0; i < k; i++) {
maxScore += cardPoints[i];
 }
intrunningSum = maxScore;
for (inti = cardPoints.length - 1, j = 1; i >= 0 && j <= k; i--, j++) {
runningSum = runningSum - cardPoints[k - j] + cardPoints[i];
maxScore = Math.max(maxScore, runningSum);
 }
returnmaxScore;
 }
 }

publicstaticclassSolution2 {
/*
 * My own implementation after looking at hints on LeetCode.
 */
publicintmaxScore(int[] cardPoints, intk) {
longsum = 0;
for (inti = 0; i < cardPoints.length; i++) {
sum += cardPoints[i];
 }
intwindowSize = cardPoints.length - k;
if (windowSize == 0) {
return (int) sum;
 }
longwindowSum = 0;
intans = 0;
for (inti = 0, j = i;
i < cardPoints.length - windowSize && j <= cardPoints.length + 1; ) {
if (j - i < windowSize) {
windowSum += cardPoints[j];
j++;
 } elseif (j - i == windowSize) {
ans = (int) Math.max(ans, sum - windowSum);
windowSum += cardPoints[j];
j++;
 } else {
windowSum -= cardPoints[i];
i++;
 }
 }
return (int) Math.max(ans, sum - windowSum);
 }
 }
}