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优化了0763.划分字母区间.md 新增贪心思路的代码逻辑
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@ -90,35 +90,43 @@ public:
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return a[0] < b[0];
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return a[0] < b[0];
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}
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}
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// 记录每个字母出现的区间
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// 记录每个字母出现的区间
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void countLabels(string s, vector<vector<int>> &hash) {
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vector<vector<int>> countLabels(string s) {
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vector<vector<int>> hash(26, vector<int>(2, INT_MIN));
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vector<vector<int>> hash_filter;
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for (int i = 0; i < s.size(); ++i) {
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for (int i = 0; i < s.size(); ++i) {
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if (hash[s[i] - 'a'][0] == INT_MIN) {
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if (hash[s[i] - 'a'][0] == INT_MIN) {
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hash[s[i] - 'a'][0] = i;
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hash[s[i] - 'a'][0] = i;
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}
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}
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hash[s[i] - 'a'][1] = i;
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hash[s[i] - 'a'][1] = i;
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}
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}
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// 去除字符串中未出现的字母所占用区间
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for (int i = 0; i < hash.size(); ++i) {
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if (hash[i][0] != INT_MIN) {
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hash_filter.push_back(hash[i]);
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}
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}
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return hash_filter;
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}
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}
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vector<int> partitionLabels(string s) {
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vector<int> partitionLabels(string s) {
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vector<int> res;
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vector<int> res;
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vector<vector<int>> hash(26, vector<int>(2, INT_MIN));
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// 这一步得到的 hash 即为无重叠区间题意中的输入样例格式:区间列表
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countLabels(s, hash);
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// 只不过现在我们要求的是区间分割点
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vector<vector<int>> hash = countLabels(s);
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// 按照左边界从小到大排序
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// 按照左边界从小到大排序
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sort(hash.begin(), hash.end(), cmp);
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sort(hash.begin(), hash.end(), cmp);
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// 记录最大右边界
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// 记录最大右边界
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int rightBoard = INT_MIN;
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int rightBoard = hash[0][1];
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int leftBoard = 0;
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int leftBoard = 0;
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for (int i = 0; i < hash.size(); ++i) {
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for (int i = 1; i < hash.size(); ++i) {
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// 过滤掉字符串中没有的字母
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// 由于字符串一定能分割,因此,
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if (hash[i][0] == INT_MIN) {
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continue;
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}
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// 一旦下一区间左边界大于当前右边界,即可认为出现分割点
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// 一旦下一区间左边界大于当前右边界,即可认为出现分割点
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if (rightBoard != INT_MIN && hash[i][0] > rightBoard) {
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if (hash[i][0] > rightBoard) {
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res.push_back(rightBoard - leftBoard + 1);
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res.push_back(rightBoard - leftBoard + 1);
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leftBoard = hash[i][0];
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leftBoard = hash[i][0];
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}
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}
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rightBoard = max(rightBoard, hash[i][1]);
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rightBoard = max(rightBoard, hash[i][1]);
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}
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}
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// 最右端
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res.push_back(rightBoard - leftBoard + 1);
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res.push_back(rightBoard - leftBoard + 1);
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return res;
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return res;
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}
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}
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