UVALive 6174 Pen Counts 规律

题目链接：点击打开链接

打一下表就能找到规律了。

#include<stdio.h>
#include<string.h>
#include<iostream>
#include<algorithm>
#include<vector>
using namespace std;
typedef long long ll;
const int N = 10010 + 2;
inline void rd(int &n){
	n = 0;
	char c = getchar();
	while(c < '0' || c > '9') c = getchar();
	while(c >= '0' && c <= '9') n *= 10, n += (c - '0'),c = getchar();
}
int a[N];
int solve(int x){
	int ans = 0;
	for(int i = 1; i <= x; i++)
	{
		if(i+i+i>x)break;
		for(int j = i; j <= x; j++)
		{
			int z = x - i- j;
			if(z<j)break;
			if (i + j > z) {
                if(j==z || i==j)ans++;
                else ans += 2;
			}
		}

	}
	return ans;
}
int main(){
//	freopen("output.txt","w+",stdout);
	/*
	for(int i = 3; i < N; i++)
		a[i] = solve(i);
	printf("a[%d]={",N);
	for(int i = 3; i < N; i++)
            printf("%d,", a[i]);
	puts("}");
	for (int i = 6; i < N; i += 2)
        printf("%d\n", a[i] - a[i - 2]);
    */
    a[3] = 1;
    a[4] = 0;
    a[5] = 1;
    a[6] = 1;
    int idx = 0, idy = 0;
    for (int i = 3; i + 2 < N; i += 2) {
        a[i + 2] = a[i] + idx;
        ++ idx;
        ++ idy;
        if (idy == 3) {
            idx -= 2;
            idy = 0;
        }
    }
    idx = idy = 0;
    for (int i = 6; i + 2 < N; i += 2) {
        a[i + 2] = a[i] + idx;
        ++ idx;
        ++ idy;
        if (idy == 3) {
            idx -= 2;
            idy = 0;
        }
    }
    int cas, x;
    scanf("%d", &cas);
    while (cas -- >0) {
        scanf("%d",&x);
        printf("%d ", x);
        scanf("%d",&x);
        printf("%d\n", a[x]);
    }
	return 0;
}
/*


*/