【POJ】1692 Crossed Matchings

经典DP，想了很久，开始想复杂了。

#include <iostream>
using namespace std;

#define MAXNUM 100

int mymax(int a, int b) {
    return (a>b) ? a:b;
}

int main() {
    int case_n;
    int a_n, b_n;
    int i, j;
    int a[MAXNUM], b[MAXNUM];
    int match[MAXNUM][MAXNUM];
    int max_a2b[MAXNUM][MAXNUM], max_b2a[MAXNUM][MAXNUM];

    cin >>case_n;

    while (case_n--) {
        cin >>a_n>>b_n;
        for (i=; i<=a_n; ++i)
            cin >>a[i];
        for (i=; i<=b_n; ++i)
            cin >>b[i];
        for (i=; i<=a_n; ++i) {
            match[i][] = ;
            max_a2b[i][] = ;
        }
        for (i=; i<=b_n; ++i) {
            match[][i] = ;
            max_b2a[i][] = ;
        }
        for (i=; i<=a_n; ++i)
            for (j=; j<=b_n; ++j) {
                if (a[i] == b[j-])
                    max_a2b[i][j] = j-;
                else
                    max_a2b[i][j] = max_a2b[i][j-];
            }
        for (i=; i<=b_n; ++i)
            for (j=; j<=a_n; ++j) {
                if (b[i] == a[j-])
                    max_b2a[i][j] = j-;
                else
                    max_b2a[i][j] = max_b2a[i][j-];
            }

        int pos_b, pos_a;
        for (i=; i<=a_n; ++i) {
            for (j=; j<=b_n; ++j) {
                match[i][j] = mymax(match[i-][j], match[i][j-]);
                pos_b = max_a2b[i][j];
                pos_a = max_b2a[j][i];
                if (pos_b> && pos_a> && a[i] != b[j]) {
                    match[i][j] = mymax(match[i][j], match[pos_a-][pos_b-]+);
                }
            }
        }

        cout <<match[a_n][b_n]<<endl;
    }

    return ;
}