【leetcode】LCP 19. 秋叶收藏集

int minimumOperations(char* leaves) {
    int n = strlen(leaves);
    int f[n][3];
    f[0][0] = (leaves[0] == 'y');
    f[0][1] = f[0][2] = f[1][2] = INT_MAX;
    for (int i = 1; i < n; ++i) {
        int isRed = (leaves[i] == 'r');
        int isYellow = (leaves[i] == 'y');
        f[i][0] = f[i - 1][0] + isYellow;
        f[i][1] = fmin(f[i - 1][0], f[i - 1][1]) + isRed;
        if (i >= 2) {
            f[i][2] = fmin(f[i - 1][1], f[i - 1][2]) + isYellow;
        }
    }
    return f[n - 1][2];
}