zigzag

zigzag.cpp

#include <cstdio>
#include <cstring>
#include <iostream>
#include <vector>
using namespace std;
void zigzag(int m, int n) {
    vector<vector<int> > ground(m);
    for (size_t i = 0; i < m; i++) {
        ground[i].resize(n);
    }
    int r = 0, c = 0;
    int index = 1;
    for (int i = 0; i < m + n - 1; i++) {
        while(r >= 0 && c >= 0 && r < m && c < n) {
            ground[r][c] = index ++;
            if (i % 2) {
                r ++;
                c --;
            } else {
                r --;
                c ++;
            }
        }
        if (c >= n) {
            c = n - 1;
            r += 2;
        }
        if (r >= m) {
            r = m - 1;
            c += 2;
        }
        if (r < 0) {
            r = 0;
        }

        if (c < 0) {
            c = 0;
        }

    }
    for (int i = 0; i < m; i++) {
        for (int j = 0; j < n; j++) {
            printf("%4d ", ground[i][j]);
        }
        printf("\n");
    }
}
int main() {
    int m, n;
    while(cin >> m >> n) {
        zigzag(m, n);
    }
    return 0;
}