pku 1221 单峰回文

#include <stdio.h>#include <string.h>#include <stdlib.h>#include <iostream>#include <string>using namespace std;#define N 500__int64 opt[N+1][N+1];//状态转移: f[i][j]为数i由最小元素为j的单峰回文组成.//则有: f[i][j] = f[i][j+1] + f[i-2*j][j] (i-2*j>=j, i-2*j == 0)//不说具体了, 你懂的.int main(){for(int i = 1; i <= N; ++i)opt[i][i] = 1;for(int i = 2; i <= N; ++i)for(int j = i-1; j >= 1; --j){opt[i][j] = opt[i][j+1];if(i-2*j >= j)opt[i][j] += opt[i-2*j][j];else if(i-2*j == 0)opt[i][j] += 1;}int n;while(scanf("%d", &n) && n)printf("%d %I64d/n", n, opt[n][1]);return 0;}