35 lines
721 B
C++
35 lines
721 B
C++
#include <iostream>
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#include <vector>
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#include <utility>
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#include <algorithm>
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using namespace std;
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struct cmp{
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bool operator()(const pair<int, int>& a, const pair<int, int>& b){
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return a.first < b.first;
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}
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};
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int main(){
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int n;
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cin >> n;
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vector<pair<int, int>> dp(n);
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//ÊäÈë
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for(int i = 0; i < n; i++){
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cin >> dp[i].first >> dp[i].second;
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}
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//°´ÕÕdp.firstÅÅÐò
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sort(dp.begin(), dp.end(), cmp());
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vector<pair<int, int>> merge;
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for(auto [l, r] : dp){
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if (merged.empty() || merged.back().second < l)
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merged.push_back({l,r});
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else
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merged.back().second = max(merged.back().second, r);
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}
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int sum = 0;
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for(auto [l, r] : merge){
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sum += r - l;
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}
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cout << sum << endl;
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return 0;
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}
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