435. 无重叠区间
先排序搞定一边,根据每个区间右边界进行排序;计算不需要删除的(判断条件更清楚)
class Solution {
public:
static bool cmp(const vector<int>& a, const vector<int>& b) {
return a[1] < b[1];
}
int eraseOverlapIntervals(vector<vector<int>>& intervals) {
if (intervals.size() == 0) return 0;
sort(intervals.begin(), intervals.end(), cmp);
int count = 1;
int end = intervals[0][1];
for (int i = 1; i < intervals.size(); i++) {
if (intervals[i][0] >= end) {
end = intervals[i][1];
count++;
}
}
return intervals.size() - count;
}
};
763.划分字母区间
class Solution {
public:
vector<int> partitionLabels(string s) {
int hash[27] = {0};
for (int i = 0; i < s.size(); i++) {
hash[s[i] - 'a'] = i;
}
vector<int> result;
int right = 0;
int left = 0;
for (int i = 0; i < s.size(); i++) {
right = max(right, hash[s[i] - 'a']);
if (i == right) {
result.push_back(right - left + 1);
left = i + 1;
}
}
return result;
}
};
56. 合并区间
push进result,然后用result.back()最后这个区间的右边界与下一个区间的左边界比较
class Solution {
public:
static bool cmp(const vector<int>& a, const vector<int>& b) {
return a[0] < b[0];
}
vector<vector<int>> merge(vector<vector<int>>& intervals) {
vector<vector<int>> result;
if (intervals.size() == 0) return result;
sort(intervals.begin(), intervals.end(), cmp);
result.push_back(intervals[0]);
for (int i = 1; i < intervals.size(); i++) {
if (result.back()[1] >= intervals[i][0]) {
result.back()[1] = max(intervals[i][1],result.back()[1]);
} else {
result.push_back(intervals[i]);
}
}
return result;
}
};