Codeforences 17C Balance

来源：互联网发布：手机ui设计软件编辑：程序博客网时间：2024/05/28 05:15
数组，开小了，暴力调了2小时才发现。。。。。
【AC代码】
////Created by just_sort 2016/12/13//Copyright (c) 2016 just_sort.All Rights Reserved//#include <ext/pb_ds/assoc_container.hpp>#include <ext/pb_ds/tree_policy.hpp>#include <ext/pb_ds/hash_policy.hpp>#include <set>#include <map>#include <queue>#include <stack>#include <cmath>#include <cstdio>#include <cstdlib>#include <cstring>#include <sstream>#include <iostream>#include <algorithm>using namespace std;using namespace __gnu_pbds;typedef long long LL;typedef pair<int, LL> pp;#define MP(x,y) make_pair(x,y)#define PI acos(-1)const int maxn = 1020;const int maxm = 1<<12;const int inf = 0x3f3f3f3f;typedef tree<int,null_type,less<int>,rb_tree_tag,tree_order_statistics_node_update>order_set;//headconst int mod = 51123987;int n, cnt, dp[200][55][55][55], nex[200][3];char s1[200], s2[200];void add(int &x, int y){    (x += y) %= mod;    if(x < 0) x += mod;}int main(){    while(scanf("%d", &n) != EOF){        scanf("%s", s1);        memset(dp, 0, sizeof(dp));        memset(nex, -1, sizeof(nex));        cnt = 0;        s2[cnt++] = s1[0];        for(int i = 1; i < n; i++){            if(s1[i] != s1[i-1]){                s2[cnt++] = s1[i];            }        }        for(int i = 0; i < cnt; i++){            for(int j = i; j < cnt; j++){                if(s2[j] == 'a' && nex[i][0] == -1){                    nex[i][0] = j;                }                if(s2[j] == 'b' && nex[i][1] == -1){                    nex[i][1] = j;                }                if(s2[j] == 'c' && nex[i][2] == -1){                    nex[i][2] = j;                }            }        }        //        int m = n / 3 + 1;        dp[0][0][0][0] = 1;        for(int i  = 1; i <= cnt; i++){            for(int ca = 0; ca <= m; ca++){                for(int cb = 0; cb <= m; cb++){                    for(int cc = 0; cc <= m; cc++){                        if(nex[i-1][0] != -1){                            //add(dp[nex[i-1][0]][ca+1][cb][cc], dp[i-1][ca][cb][cc]);                            dp[nex[i-1][0]][ca+1][cb][cc] += dp[i-1][ca][cb][cc];                            dp[nex[i-1][0]][ca+1][cb][cc] %= mod;                        }                        if(nex[i-1][1] != -1){                            //add(dp[nex[i-1][1]][ca][cb+1][cc], dp[i-1][ca][cb][cc]);                            dp[nex[i-1][1]][ca][cb+1][cc] += dp[i-1][ca][cb][cc];                            dp[nex[i-1][1]][ca][cb+1][cc] %= mod;                        }                        if(nex[i-1][2] != -1){                            //add(dp[nex[i-1][2]][ca][cb][cc+1], dp[i-1][ca][cb][cc]);                            dp[nex[i-1][2]][ca][cb][cc+1] += dp[i-1][ca][cb][cc];                            dp[nex[i-1][2]][ca][cb][cc+1] %= mod;                        }                    }                }            }        }        int ans = 0;        if(n % 3 == 0){            for(int i = 0; i < cnt; i++){                //add(ans, dp[i][n/3][n/3][n/3]);                ans += dp[i][n/3][n/3][n/3]; ans %= mod;            }        }        else if(n % 3 == 1){            for(int i = 0; i < cnt; i++){//                add(ans, dp[i][n/3+1][n/3][n/3]);//                add(ans, dp[i][n/3][n/3+1][n/3]);//                add(ans, dp[i][n/3][n/3][n/3+1]);                  ans += dp[i][n/3+1][n/3][n/3]; ans %= mod;                  ans += dp[i][n/3][n/3+1][n/3]; ans %= mod;                  ans += dp[i][n/3][n/3][n/3+1]; ans %= mod;            }        }        else{            for(int i = 0; i < cnt; i++){//                add(ans, dp[i][n/3+1][n/3+1][n/3]);//                add(ans, dp[i][n/3+1][n/3][n/3+1]);//                add(ans, dp[i][n/3][n/3+1][n/3+1]);                  ans += dp[i][n/3+1][n/3+1][n/3]; ans %= mod;                  ans += dp[i][n/3+1][n/3][n/3+1]; ans %= mod;                  ans += dp[i][n/3][n/3+1][n/3+1]; ans %= mod;            }        }        ans = ans % mod;        if(ans < 0) ans += mod;        printf("%d\n", ans);    }    return 0;}
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