76 lines
2.0 KiB
C++
76 lines
2.0 KiB
C++
#include <cstdio>
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#include <cstdlib>
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#include <cmath>
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#include <cstring>
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#include <algorithm>
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#include <vector>
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#include <stack>
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#include <queue>
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#include <set>
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#define LL long long
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#define mod 1000000007
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#define M 1005
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#define INF 0x7fffffff
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using namespace std;
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struct Point
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{
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int x, y;
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bool operator < (const Point &temp) const
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{
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if(x!=temp.x) return x<temp.x;
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else return y<temp.y;
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}
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int readPoint()
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{
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return scanf("%d%d", &x, &y);
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}
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} p[M];
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int n, m, k;
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int val[M];
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set<int>sset;
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set<int>::iterator it;
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int main ()
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{
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while(~scanf("%d%d%d", &n, &m, &k))
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{
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for(int i = 1; i <= k; ++i)
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{
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p[i].readPoint();
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val[i] = p[i].x;
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}
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sort(p+1, p+1+k);
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sort(val+1, val+1+k);
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int tot = unique(val+1, val+1+k) - val;
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val[0] = 0;
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val[tot] = n+1;
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LL ans = 0;
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for(int i = 1; i < tot; ++i)
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{
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LL tt = 0;
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int pre = val[i]-val[i-1];
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int r;
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for(r = 1; r <= k && p[r].x < val[i]; ++r);
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sset.clear();
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sset.insert(0);
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sset.insert(m+1);
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for(int j = i; j < tot; ++j)
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{
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int top, bottom;
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for( ; r <= k && p[r].x == val[j]; ++r)
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{
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if(sset.count(p[r].y)) continue;
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it = sset.lower_bound(p[r].y);
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top = *it;
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bottom = *(--it);
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tt = (tt+(LL)(top-p[r].y)*(p[r].y-bottom)%mod)%mod;
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sset.insert(p[r].y);
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}
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int rear = val[j+1]-val[j];
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ans = (ans+tt*rear%mod*pre%mod)%mod;
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}
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}
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printf("%I64d\n", ans);
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}
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return 0;
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}
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