c_cpp 最小窗口子串。给定一个字符串S和一个字符串T，找到S中的最小窗口，它将包含在Comple中的T中的所有字符

Posted 2021-05-14

#include <iostream>
#include <string>
#include <unordered_map>
#include <climits>
#include <vector>
using namespace std;

string minimum_window_substring(const string &s, const string &p) {
    if(p.empty() || s.empty() || s.size() < p.size()) return "";
    
    int left = 0, right = 0, ns = s.size(), np = p.size();
    int start_pos = 0, min_len = INT_MAX;
    
    vector<int> total(256, 0), sofar(256, 0);
    
    for(char c : p) total[c]++;   //      should be p not s !!!!!!!
    
    int curr_len = 0;
    for(; right < ns; right++) {
        char c = s[right];
        if(total[c] == 0) continue;
        else sofar[c]++;
        if(sofar[c] <= total[c]) curr_len++;
        
        while (curr_len == np) {
            char ch = s[left];
            if(total[ch] == 0) left++;
            else if (sofar[ch] > total[ch]) {
                sofar[ch]--;
                left++;
            } else break;
        }
        if(curr_len == np) {
            if(min_len > right - left + 1) {
                min_len = right - left + 1;
                start_pos = left;
            }
        }
    }
    if(curr_len < np) return "";
    return s.substr(start_pos, min_len);    
}

int main()
{
   cout << minimum_window_substring("aaabcdfefbbcf", "bcf");
   return 0;
}