LeeCode Practice Journal | Day30_GA04

452. 用数量最少的箭引爆气球

题目：452. 用最少数量的箭引爆气球 - 力扣（LeetCode）
题解：代码随想录 (programmercarl.com)
先排序再计算重叠区域？
一遍过，开心

solution

public class Solution {public int FindMinArrowShots(int[][] points) {var sortedpoints = points.OrderBy(p => p[0]).ToList();int left = sortedpoints[0][0];int right = sortedpoints[0][1];int count = 1;for(int i = 1; i < sortedpoints.Count; i ++){if(sortedpoints[i][0] > right){count ++;left = sortedpoints[i][0];right = sortedpoints[i][1];}else{left = sortedpoints[i][0];right = sortedpoints[i][1] < right ? sortedpoints[i][1] : right;}}return count;}
}

summary

435. 无重叠区间

题目：435. 无重叠区间 - 力扣（LeetCode）
题解：代码随想录 (programmercarl.com)
重叠的时候怎样移除可以使覆盖范围尽可能小

solution

public class Solution {public int EraseOverlapIntervals(int[][] intervals) {Array.Sort(intervals,(a, b) => a[0].CompareTo(b[0]));int result = 0;for(int i = 1; i < intervals.Length; i ++){if(intervals[i][0] < intervals[i - 1][1]){result ++;intervals[i][1] = intervals[i][1] < intervals[i - 1][1] ? intervals[i][1] : intervals[i - 1][1];}}return result;}
}

summary

key：

理解是否重叠只和当前区域的左边界与上一区域的右边界的关系有关

763. 划分字母区间

题目：763. 划分字母区间 - 力扣（LeetCode）
题解：代码随想录 (programmercarl.com)

solution

public class Solution
{public IList<int> PartitionLabels(string s){var lastIndex = new Dictionary<char, int>();for (int i = 0; i < s.Length; i++){lastIndex[s[i]] = i;}var result = new List<int>();int start = 0, end = 0;for (int i = 0; i < s.Length; i++){end = Math.Max(end, lastIndex[s[i]]);if (i == end){result.Add(end - start + 1);start = i + 1;}}return result;}
}

summary