Submission #71348437

Source Code Expand

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#include <stdio.h>
#define MOD_BY 1000000007
int add(int a, int b) {
  return a + b - MOD_BY * (a + b >= MOD_BY);
}
int N;
char s[4096];
int memo[4096][4096];
int main(void) {
  int pos, available;
  if (scanf("%d", &N) != 1) return 1;
  if (scanf("%4095s", s) != 1) return 1;
  memo[N][0] = 1;
  for (pos = N - 1; pos >= 0; pos--) {
    for (available = 0; available <= N - pos; available++) {
      int unavailable = N - pos - available; /* この要素の候補ではない要素の数を計算する */
 
 
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#include <stdio.h>

#define MOD_BY 1000000007

int add(int a, int b) {
	return a + b - MOD_BY * (a + b >= MOD_BY);
}

int N;
char s[4096];

int memo[4096][4096];

int main(void) {
	int pos, available;
	if (scanf("%d", &N) != 1) return 1;
	if (scanf("%4095s", s) != 1) return 1;
	memo[N][0] = 1;
	for (pos = N - 1; pos >= 0; pos--) {
		for (available = 0; available <= N - pos; available++) {
			int unavailable = N - pos - available; /* この要素の候補ではない要素の数を計算する */
			int ans = 0;
			int i;
			for (i = 0; i < available; i++) {
				int next_available;
				if ((pos == 0 ? '<' : s[pos - 1]) == s[pos]) {
					/* 同じ方向 → 今の所より「上」のみを次に使える */
					next_available = available - i - 1;
				} else {
					/* 違う方向 → 今の所より「下」のみを次に使える */
					next_available = unavailable + i;
				}
				ans = add(ans, memo[pos + 1][next_available]);
			}
			memo[pos][available] = ans;
		}
	}
	printf("%d\n", memo[0][N]);
	return 0;
}

Submission Info

Judge Result