题目：https://vjudge.net/problem/UVA-12504
思路：用集合的思想，旧字典与新字典的差集就是减少部分，新字典与旧字典的差集就是增加部分，新旧字典的交集中键值改变的部分就是修改部分。
注：读入时别忘单独处理空集。
代码：C++11
#include <iostream> #include <string> #include <cstring> #include <cctype> #include <cstdio> #include <set> #include <map> #include <algorithm> using namespace std; map<string, string> oridata; map<string, string> newdata; set<string> orikey; set<string> newkey; set<string> increase; set<string> decrease; set<string> change; void getdata(map<string, string> &nowdata, set<string> &nowkey) { bool keyflag = true; getchar(); string key, value; while(1) { char c; c = getchar(); if(c=='}') { if(keyflag) { getchar(); return ; } nowdata[key] = value; nowkey.insert(key); getchar(); return ; } else if(c==':') { keyflag = !keyflag; } else if(c==',') { keyflag = !keyflag; nowdata[key] = value; nowkey.insert(key); key.clear(); value.clear(); } else if(keyflag) { key.push_back(c); } else { value.push_back(c); } } } void print(set<string> key) { bool first = true; for(auto &t:key) { if(first) { first = false; } else { printf(","); } cout << t << flush; } cout << endl; } int main() { int T; cin >> T; getchar(); while(T--) { oridata.clear(); newdata.clear(); orikey.clear(); newkey.clear(); increase.clear(); decrease.clear(); change.clear(); getdata(oridata, orikey); getdata(newdata, newkey); set_difference(newkey.begin(), newkey.end(), orikey.begin(), orikey.end(), inserter(increase, increase.begin())); set_difference(orikey.begin(), orikey.end(), newkey.begin(), newkey.end(), inserter(decrease, decrease.begin())); set<string> intersection; set_intersection(orikey.begin(), orikey.end(), newkey.begin(), newkey.end(), inserter(intersection, intersection.begin())); for(auto &t: intersection) { if(oridata[t]!=newdata[t]) { change.insert(t); } } if(increase.empty()&&decrease.empty()&&change.empty()) { cout << "No changes" << endl; } if(!increase.empty()) { printf("+"); print(increase); } if(!decrease.empty()) { printf("-"); print(decrease); } if(!change.empty()) { printf("*"); print(change); } cout << endl; } return 0; }
