30 lines
716 B
C++
30 lines
716 B
C++
#include <stdio.h>
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#include <cstring>
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#include <algorithm>
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using namespace std;
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int dp[510][510];
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int tt[510][510], an[510];
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int main()
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{
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int i, j, k;
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int n, a, b;
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while(scanf("%d", &n) != EOF)
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{
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memset(dp, 0, sizeof(dp));
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memset(an, 0, sizeof(an));
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memset(tt, 0, sizeof(tt));
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for(i = 0; i < n; ++i) {
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scanf("%d %d", &a, &b);
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if(a+b < n && tt[a][n-b] < (n-a-b))
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tt[a][n-b]++;
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}
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for(i = 1; i <= n; ++i)
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for(j = 0; j < i; ++j) {
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dp[j][i] = an[j]+tt[j][i];
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an[i] = max(an[i], dp[j][i]);
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}
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printf("%d\n", an[n]);
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}
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return 0;
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}
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