Codeforces Round #260 (Div. 1) A. Boredom

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简单动态规划

用计数排序统计数字的个数

dp[ i ][ 0 ]表示不删除 i ，dp[ i ][ 1 ]表示删除 i

dp[ i ][ 0 ] = max( dp[ i-1 ][ 1 ] , dp[ i-1 ][ 0 ] );
dp[ i ][ 1 ] = dp[ i-1 ][ 0 ] + i * a[ i ];

#include <algorithm>#include <iostream>#include <iomanip>#include <cstring>#include <climits>#include <complex>#include <fstream>#include <cassert>#include <cstdio>#include <bitset>#include <vector>#include <deque>#include <queue>#include <stack>#include <ctime>#include <set>#include <map>#include <cmath>#define CLR(x,y) memset(x,y,sizeof(x))#define eps 1e-9#define INF 0x3f3f3f3fusing namespace std;typedef long long ll;typedef long double ld;typedef pair<ll, ll> pll;typedef complex<ld> point;typedef pair<int, int> pii;typedef pair<pii, int> piii;template<class T>inline bool read(T &n){    T x = 0, tmp = 1; char c = getchar();    while((c < '0' || c > '9') && c != '-' && c != EOF) c = getchar();    if(c == EOF) return false;    if(c == '-') c = getchar(), tmp = -1;    while(c >= '0' && c <= '9') x *= 10, x += (c - '0'),c = getchar();    n = x*tmp;    return true;}template <class T>inline void write(T n){    if(n < 0)    {        putchar('-');        n = -n;    }    int len = 0,data[20];    while(n)    {        data[len++] = n%10;        n /= 10;    }    if(!len) data[len++] = 0;    while(len--) putchar(data[len]+48);}//-----------------------------------const int MAXN=100010;ll a[MAXN],dp[2][2];int main(){int n,temp,maxn=-INF;while(read(n)){for(int i=0;i<n;i++){read(temp);a[temp]++;maxn=max(temp,maxn);}int k=1;for(int i=1;i<=maxn;i++,k^=1){dp[k][0]=max(dp[!k][1],dp[!k][0]);dp[k][1]=dp[!k][0]+i*a[i];}dp[k][1]=max(dp[!k][1],dp[k][1]);dp[k][0]=max(dp[!k][0],dp[k][0]);printf("%I64d\n",max(dp[k][1],dp[k][0]));CLR(a,0);CLR(dp,0);}return 0;}

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