caioj 1073 动态规划入门（三维一边推：最长公共子序列加强版（三串LCS））

三维的与二维大同小异，看代码。

#include<cstdio>
#include<cstring>
#include<algorithm>
#define REP(i, a, b) for(int i = (a); i < (b); i++)
using namespace std;

const int MAXN = 112;
char a[MAXN], b[MAXN], c[MAXN];
int f[MAXN][MAXN][MAXN], path[MAXN][MAXN][MAXN];

void print(int x, int y, int z)
{
	int t = path[x][y][z];
	if(t == 1)
	{
		print(x - 1, y - 1, z - 1);
		putchar(a[x]);
	}
	else if(t == 2) print(x - 1, y, z);
	else if(t == 3) print(x, y - 1, z);
	else if(t == 4) print(x, y, z - 1);
}

int main()
{
	scanf("%s%s%s", a + 1, b + 1, c + 1);
	int lena = strlen(a + 1), lenb = strlen(b + 1), lenc = strlen(c + 1);

	REP(i, 1, lena + 1)
		REP(j, 1, lenb + 1)
			REP(k, 1, lenc + 1)
			{
				if(a[i] == b[j] && b[j] == c[k])
				{
					f[i][j][k] = f[i-1][j-1][k-1] + 1;
					path[i][j][k] = 1;
				}
				else
				{
					f[i][j][k] = max(f[i-1][j][k], max(f[i][j-1][k], f[i][j][k-1]));
					if(f[i][j][k] == f[i-1][j][k]) path[i][j][k] = 2;
					if(f[i][j][k] == f[i][j-1][k]) path[i][j][k] = 3;
					if(f[i][j][k] == f[i][j][k-1]) path[i][j][k] = 4;
				}
			}
	printf("%d\n", f[lena][lenb][lenc]);
	print(lena, lenb, lenc);

	return 0;
}