Day31 贪心5 | LeetCode 435. 无重叠区间， 763. 划分字母区间，56. 合并区间

最新推荐文章于 2025-12-09 14:04:42 发布

原创最新推荐文章于 2025-12-09 14:04:42 发布 · 103 阅读

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LeetCode 435. 无重叠区间

class Solution {
public:
    
    static bool cmp (const vector<int>& L, const vector<int>& R){
        return L[1] < R[1];
    }

    int eraseOverlapIntervals(vector<vector<int>>& intervals) {
        if (intervals.size() < 2){
            return 0;
        }
        int remove_count = 0;
        sort(intervals.begin(), intervals.end(), cmp);
        int end = intervals[0][1];

        for (int i = 1; i < intervals.size(); i++){
            if (intervals[i][0] < end){
                remove_count++;

            }else {
                end = intervals[i][1];
            }
        }
        return remove_count;
    }
};

LeetCode 763. 划分字母区间

class Solution {
public:
    vector<int> partitionLabels(string s) {
        vector<int> ans;
        int hash[26] ={0};
        for (int i = 0; i < s.size(); i++){
            hash[s[i] - 'a'] = i;
        }
        int left = 0;
        int right = 0;
        for (int i = 0; i < s.size(); i++){
            //找到字符最远边界
            right = max(right, hash[s[i] - 'a']);
            if(i == right){
                ans.push_back(right - left + 1);
                left = right + 1;
            }
        }
        return ans;
    }
};

LeetCode 56. 合并区间

1.自己实现

class Solution {
public:

    static bool cmp (const vector<int>& L, const vector<int>& R){
        return L[0] < R[0];
    }

    vector<vector<int>> merge(vector<vector<int>>& intervals) {
        if (intervals.size() < 2){
            return intervals;
        }
        vector<vector<int>> ans;
        sort(intervals.begin(), intervals.end(), cmp);
        int start = intervals[0][0];
        int end = intervals[0][1];
        for (int i = 1; i < intervals.size(); i++){
            if (intervals[i][0] <= end){
                end = max(end, intervals[i][1]);
            }else {
                ans.emplace_back(vector({start, end}));
                start = intervals[i][0];
                end = intervals[i][1];
            }
        }
        ans.emplace_back(vector({start, end}));
        return ans;

    }
};

2.Carl版本

class Solution {
public:
    vector<vector<int>> merge(vector<vector<int>>& intervals) {
        if (intervals.size() < 2) {
            return intervals;
        }
        sort(intervals.begin(), intervals.end(), [](const vector<int>& L, const vector<int>& R){return L[0] < R[0];});
        vector<vector<int>> ans;
        ans.emplace_back(intervals[0]);
        for (int i = 1; i < intervals.size(); i++){
            if (intervals[i][0] <= ans.back()[1]){
                ans.back()[1] = max(ans.back()[1], intervals[i][1]);
            }else {
                ans.emplace_back(intervals[i]);
            }
        }
        return ans;
    }
};