day36||452. 用最少数量的箭引爆气球435. 无重叠区间 763.划分字母区间

452. 用最少数量的箭引爆气球

class Solution {public int findMinArrowShots(int[][] points) {//Arrays.sort(points,(a,b)->a[0]-b[0]);//这句话会溢出Arrays.sort(points,(a,b)->Integer.compare(a[0],b[0]));int count = 1;for(int i = 1;i<points.length;i++){if(points[i][0]>points[i-1][1]){count++;}else{points[i][1] = Math.min(points[i-1][1],points[i][1]);}}return count;}
}

435. 无重叠区间 

class Solution {public int eraseOverlapIntervals(int[][] intervals) {Arrays.sort(intervals,(a,b)->Integer.compare(a[0],b[0]));int count = 0;for(int i = 1;i<intervals.length;i++){if(intervals[i][0]<intervals[i-1][1]){count++;intervals[i][1] = Math.min(intervals[i][1],intervals[i-1][1]);}}return count;}
}

763.划分字母区间

跟卡尔的写法稍微有些区别，但是无伤大雅。

class Solution {public List<Integer> partitionLabels(String s) {int[] hash = new int[26];for(int i = 0;i<s.length();i++){hash[s.charAt(i)-'a'] = i;}List<Integer> res = new ArrayList<>();int count = 0;int max = 0;for(int i = 0;i<s.length();i++){max = Math.max(hash[s.charAt(i)-'a'],max);count++;if(i == max){res.add(count);count = 0;}}return res;}
}